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Bartmann MG, Glassner S, Sistani M, Rurali R, Palummo M, Cartoixà X, Smoliner J, Lugstein A. Electronic Transport Modulation in Ultrastrained Silicon Nanowire Devices. ACS APPLIED MATERIALS & INTERFACES 2024. [PMID: 38899807 DOI: 10.1021/acsami.4c05477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
In this work, we explore the effect of ultrahigh tensile strain on electrical transport properties of silicon. By integrating vapor-liquid-solid-grown nanowires into a micromechanical straining device, we demonstrate uniaxial tensile strain levels up to 9.5%. Thereby the triply degenerated phonon dispersion relation at the Γ-point of silicon disentangle and the longitudinal phonon modes are used to precisely determine the extent of mechanical strain. Simultaneous electrical transport measurements showed a significant enhancement in the electrical conductance. Aside from considerable reduction of the Si bulk resistivity due to strain-induced band gap narrowing, comparison with quasi-particle GW calculations further reveals that the effective Schottky barrier height at the electrical contacts undergoes a substantial reduction. For these reasons, nanowire devices with ultrastrained channels may be promising candidates for future applications of high-performance silicon-based devices.
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Affiliation(s)
- Maximilian G Bartmann
- Institute for Solid State Electronics, Technische Universität Wien, Gußhausstraße 25-25a, 1040 Vienna, Austria
| | - Sebastian Glassner
- Institute for Solid State Electronics, Technische Universität Wien, Gußhausstraße 25-25a, 1040 Vienna, Austria
| | - Masiar Sistani
- Institute for Solid State Electronics, Technische Universität Wien, Gußhausstraße 25-25a, 1040 Vienna, Austria
| | - Riccardo Rurali
- Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, 08193 Bellaterra, Spain
| | - Maurizia Palummo
- Dipartimento di Fisica and INFN, Università di Roma "Tor Vergata", 00133 Roma, Italy
| | - Xavier Cartoixà
- Departament d'Enginyeria Electrònica, Universitat Autònoma de Barcelona, Bellaterra 08193, Barcelona, Spain
| | - Jürgen Smoliner
- Institute for Solid State Electronics, Technische Universität Wien, Gußhausstraße 25-25a, 1040 Vienna, Austria
| | - Alois Lugstein
- Institute for Solid State Electronics, Technische Universität Wien, Gußhausstraße 25-25a, 1040 Vienna, Austria
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2
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Engelsen NJ, Beccari A, Kippenberg TJ. Ultrahigh-quality-factor micro- and nanomechanical resonators using dissipation dilution. NATURE NANOTECHNOLOGY 2024; 19:725-737. [PMID: 38443697 DOI: 10.1038/s41565-023-01597-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 12/14/2023] [Indexed: 03/07/2024]
Abstract
Mechanical resonators are widely used in sensors, transducers and optomechanical systems, where mechanical dissipation sets the ultimate limit to performance. Over the past 15 years, the quality factors in strained mechanical resonators have increased by four orders of magnitude, surpassing the previous state of the art achieved in bulk crystalline resonators at room temperature and liquid helium temperatures. In this Review, we describe how these advances were made by leveraging 'dissipation dilution'-where dissipation is reduced through a combination of static tensile strain and geometric nonlinearity in dynamic strain. We then review the state of the art in strained nanomechanical resonators and discuss the potential for even higher quality factors in crystalline materials. Finally, we detail current and future applications of dissipation-diluted mechanical resonators.
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Affiliation(s)
- Nils Johan Engelsen
- Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, Gothenburg, Sweden.
| | - Alberto Beccari
- Instutute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
- Center for Quantum Science and Engineering, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
| | - Tobias Jan Kippenberg
- Instutute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
- Center for Quantum Science and Engineering, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
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3
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Badawy G, Bakkers EPAM. Electronic Transport and Quantum Phenomena in Nanowires. Chem Rev 2024; 124:2419-2440. [PMID: 38394689 PMCID: PMC10941195 DOI: 10.1021/acs.chemrev.3c00656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Revised: 01/26/2024] [Accepted: 02/08/2024] [Indexed: 02/25/2024]
Abstract
Nanowires are natural one-dimensional channels and offer new opportunities for advanced electronic quantum transport experiments. We review recent progress on the synthesis of nanowires and methods for the fabrication of hybrid semiconductor/superconductor systems. We discuss methods to characterize their electronic properties in the context of possible future applications such as topological and spin qubits. We focus on group III-V (InAs and InSb) and group IV (Ge/Si) semiconductors, since these are the most developed, and give an outlook on other potential materials.
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Affiliation(s)
- Ghada Badawy
- Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
| | - Erik P. A. M. Bakkers
- Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
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4
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Liu P, Schleusener A, Zieger G, Bochmann A, van Spronsen MA, Sivakov V. Nanostructured Silicon Matrix for Materials Engineering. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2206318. [PMID: 36642786 DOI: 10.1002/smll.202206318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 12/20/2022] [Indexed: 06/17/2023]
Abstract
Tin-containing layers with different degrees of oxidation are uniformly distributed along the length of silicon nanowires formed by a top-down method by applying metalorganic chemical vapor deposition. The electronic and atomic structure of the obtained layers is investigated by applying nondestructive surface-sensitive X-ray absorption near edge spectroscopy using synchrotron radiation. The results demonstrated, for the first time, a distribution effect of the tin-containing phases in the nanostructured silicon matrix compared to the results obtained for planar structures at the same deposition temperatures. The amount and distribution of tin-containing phases can be effectively varied and controlled by adjusting the geometric parameters (pore diameter and length) of the initial matrix of nanostructured silicon. Due to the occurrence of intense interactions between precursor molecules and decomposition by-products in the nanocapillary, as a consequence of random thermal motion of molecules in the nanocapillary, which leads to additional kinetic energy and formation of reducing agents, resulting in effective reduction of tin-based compounds to a metallic tin state for molecules with the highest penetration depth in the nanostructured silicon matrix. This effect will enable clear control of the phase distributions of functional materials in 3D matrices for a wide range of applications.
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Affiliation(s)
- Poting Liu
- Leibniz Institute of Photonic Technology, Albert-Einstein Str. 9, 07745, Jena, Germany
- Friedrich Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany
| | - Alexander Schleusener
- Leibniz Institute of Photonic Technology, Albert-Einstein Str. 9, 07745, Jena, Germany
- Friedrich Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany
- Istituto Italiano di Tecnologia, Via Morego 30, Genova, 16163, Italy
| | - Gabriel Zieger
- Leibniz Institute of Photonic Technology, Albert-Einstein Str. 9, 07745, Jena, Germany
| | - Arne Bochmann
- Ernst Abbe University of Applied Science, Carl-Zeiss-Promenade 2, 07745, Jena, Germany
| | | | - Vladimir Sivakov
- Leibniz Institute of Photonic Technology, Albert-Einstein Str. 9, 07745, Jena, Germany
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5
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Burt D, Zhang L, Jung Y, Joo HJ, Kim Y, Chen M, Son B, Fan W, Ikonic Z, Tan CS, Nam D. Tensile strained direct bandgap GeSn microbridges enabled in GeSn-on-insulator substrates with residual tensile strain. OPTICS LETTERS 2023; 48:735-738. [PMID: 36723576 DOI: 10.1364/ol.476517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 12/15/2022] [Indexed: 06/18/2023]
Abstract
Despite having achieved drastically improved lasing characteristics by harnessing tensile strain, the current methods of introducing a sizable tensile strain into GeSn lasers require complex fabrication processes, thus reducing the viability of the lasers for practical applications. The geometric strain amplification is a simple technique that can concentrate residual and small tensile strain into localized and large tensile strain. However, the technique is not suitable for GeSn due to the intrinsic compressive strain introduced during the conventional epitaxial growth. In this Letter, we demonstrate the geometrical strain amplification in GeSn by employing a tensile strained GeSn-on-insulator (GeSnOI) substrate. This work offers exciting opportunities in developing practical wavelength-tunable lasers for realizing fully integrated photonic circuits.
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Zheng X, Liu Y, Qiu J, Liu G. Structural Optimization of Graphene Triangular Lattice Phononic Crystal Based on Dissipation Dilution Theory. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:2807. [PMID: 36014672 PMCID: PMC9415148 DOI: 10.3390/nano12162807] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 07/16/2022] [Accepted: 07/20/2022] [Indexed: 06/15/2023]
Abstract
Nanomechanical resonators offer brilliant mass and force sensitivity applied in many fields, owing to a low mass m and high-quality factor Q. However, in vibrating process, resonant energy is inevitably dissipated. Typically, quality factor does not surpass the inverse of the material loss angle φ. Recently, some exceptions emerged in the use of highly stressed silicon nitride material. As yet, it is interpreted that the pre-stress seems to "dilute" the intrinsic energy dissipation according to the Zener model. Is there any other material that could further break the 1/φ limit and achieve higher quality factors? In our previous research, through theoretical calculation and finite element simulation, we have proved that graphene's quality factor is two orders of magnitude larger than silicon nitride, on account of the extremely thin thickness of graphene. Based on this, we further optimize the structure of phononic crystals to achieve higher quality factors, in terms of duty cycle and cell size. Through simulation analysis, the quality factor could improve with a larger duty cycle and bigger cell size of triangular lattice phononic crystal. Unexpectedly, the Q amplification coefficient of the 3 × 5-cell structure, which is the least number to compose a phononic crystal with a central defect area, is the highest. In contrast, the minimal cell-number structure in hexagonal lattice could not achieve the brilliant dissipation dilution effect as well as the triangular one. Then we consider how overall size and stress influence quality factor and, furthermore, compare theoretical calculation and finite simulation. Lastly, we start from the primitive 3 × 5 cells, constantly adding cells to the periphery. Through simulation, to our surprise, the largest Q amplification coefficient does not belong to the largest structure, instead originating from the moderate one consisting of 7 × 13 cells.
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Srivastava RP, Khang DY. Structuring of Si into Multiple Scales by Metal-Assisted Chemical Etching. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2005932. [PMID: 34013605 DOI: 10.1002/adma.202005932] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 11/18/2020] [Indexed: 05/27/2023]
Abstract
Structuring Si, ranging from nanoscale to macroscale feature dimensions, is essential for many applications. Metal-assisted chemical etching (MaCE) has been developed as a simple, low-cost, and scalable method to produce structures across widely different dimensions. The process involves various parameters, such as catalyst, substrate doping type and level, crystallography, etchant formulation, and etch additives. Careful optimization of these parameters is the key to the successful fabrication of Si structures. In this review, recent additions to the MaCE process are presented after a brief introduction to the fundamental principles involved in MaCE. In particular, the bulk-scale structuring of Si by MaCE is summarized and critically discussed with application examples. Various approaches for effective mass transport schemes are introduced and discussed. Further, the fine control of etch directionality and uniformity, and the suppression of unwanted side etching are also discussed. Known application examples of Si macrostructures fabricated by MaCE, though limited thus far, are presented. There are significant opportunities for the application of macroscale Si structures in different fields, such as microfluidics, micro-total analysis systems, and microelectromechanical systems, etc. Thus more research is necessary on macroscale MaCE of Si and their applications.
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Affiliation(s)
- Ravi P Srivastava
- Soft Electronic Materials and Devices Laboratory, Department of Materials Science and Engineering, Yonsei University, Seoul, 03722, Korea
| | - Dahl-Young Khang
- Soft Electronic Materials and Devices Laboratory, Department of Materials Science and Engineering, Yonsei University, Seoul, 03722, Korea
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8
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Csiszár G, Lawitzki R, Everett C, Schmitz G. Elastic Behavior of Nb 2O 5/Al 2O 3 Core-Shell Nanowires in Terms of Short-Range-Order Structures. ACS APPLIED MATERIALS & INTERFACES 2021; 13:24238-24249. [PMID: 33988356 DOI: 10.1021/acsami.1c02936] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Single-crystalline niobium pentoxide nanowires (NWs) of length 10-15 μm and diameter 100-200 nm are synthesized by thermal oxidation of niobium substrates in a mild vacuum (3-10 mbar). Amorphous Al2O3 shells of varying thicknesses (10, 30, 40, and 50 nm) are deposited on top of the wires using atomic layer deposition. Bending tests of the uncoated Nb2O5 NWs and the Nb2O5/Al2O3 core-shell NWs are carried out inside a scanning electron microscope using a micromanipulator with a force measurement tip. The experimental deflection curves are modeled with Euler-Bernoulli (E-B) beam theory, and the Young's modulus is manipulated to determine the best fit. The Nb2O5 NWs with no shell are determined to have a Young's modulus of 67 ± 10 GPa, which agrees with the published data on Nb2O5 thin films. For core-shell NWs, only small deflections of the wires with 10 and 30 nm thick shells can be fitted with the E-B model when utilizing constant Young's modulus values of 67 GPa for the Nb2O5 core and about 160 GPa for the Al2O3 shell. When allowing for a change in the Young's modulus of the Al2O3 shell, the Young's modulus is determined to be at 120 ± 10 GPa for 10 nm and 145 ± 12 GPa for 30 nm at the highest applied load. For thicknesses of 40 nm and 50 nm, we observed a reduced but constant 120 ± 11 and 111 ± 10 GPa, respectively. Such behavior may result from structural disordering of the amorphous Al2O3 through reducing fractions of the densely packed polyhedra, while the fractions of the loosely packed polyhedra increase as a result of the increasing strain or the fabrication process. The increased disorder is associated with increased average interatomic spacing. Thus, the atomic bonding force and also the Young's modulus decrease.
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Affiliation(s)
- Gábor Csiszár
- Department of Materials Physics, Institute for Materials Science, University of Stuttgart, Stuttgart 70569, Germany
| | - Robert Lawitzki
- Department of Materials Physics, Institute for Materials Science, University of Stuttgart, Stuttgart 70569, Germany
| | - Christopher Everett
- Department of Functional Materials, Faculty of Physics, Technical University Munich, Garching 85747, Germany
| | - Guido Schmitz
- Department of Materials Physics, Institute for Materials Science, University of Stuttgart, Stuttgart 70569, Germany
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9
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Jung Y, Kim Y, Burt D, Joo HJ, Kang DH, Luo M, Chen M, Zhang L, Tan CS, Nam D. Biaxially strained germanium crossbeam with a high-quality optical cavity for on-chip laser applications. OPTICS EXPRESS 2021; 29:14174-14181. [PMID: 33985141 DOI: 10.1364/oe.417330] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 04/07/2021] [Indexed: 06/12/2023]
Abstract
The creation of CMOS compatible light sources is an important step for the realization of electronic-photonic integrated circuits. An efficient CMOS-compatible light source is considered the final missing component towards achieving this goal. In this work, we present a novel crossbeam structure with an embedded optical cavity that allows both a relatively high and fairly uniform biaxial strain of ∼0.9% in addition to a high-quality factor of >4,000 simultaneously. The induced biaxial strain in the crossbeam structure can be conveniently tuned by varying geometrical factors that can be defined by conventional lithography. Comprehensive photoluminescence measurements and analyses confirmed that optical gain can be significantly improved via the combined effect of low temperature and high strain, which is supported by a three-fold reduction of the full width at half maximum of a cavity resonance at ∼1,940 nm. Our demonstration opens up the possibility of further improving the performance of germanium lasers by harnessing geometrically amplified biaxial strain.
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10
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Al-Abri R, Choi H, Parkinson P. Measuring, controlling and exploiting heterogeneity in optoelectronic nanowires. JPHYS PHOTONICS 2021. [DOI: 10.1088/2515-7647/abe282] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Abstract
Fabricated from ZnO, III-N, chalcogenide-based, III-V, hybrid perovskite or other materials, semiconductor nanowires offer single-element and array functionality as photovoltaic, non-linear, electroluminescent and lasing components. In many applications their advantageous properties emerge from their geometry; a high surface-to-volume ratio for facile access to carriers, wavelength-scale dimensions for waveguiding or a small nanowire-substrate footprint enabling heterogeneous growth. However, inhomogeneity during bottom-up growth is ubiquitous and can impact morphology, geometry, crystal structure, defect density, heterostructure dimensions and ultimately functional performance. In this topical review, we discuss the origin and impact of heterogeneity within and between optoelectronic nanowires, and introduce methods to assess, optimise and ultimately exploit wire-to-wire disorder.
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11
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Wang Y, Jin S, Wang Q, Wu M, Yao S, Liao P, Kim MJ, Cheng GJ, Wu W. Parallel Nanoimprint Forming of One-Dimensional Chiral Semiconductor for Strain-Engineered Optical Properties. NANO-MICRO LETTERS 2020; 12:160. [PMID: 34138155 PMCID: PMC7770755 DOI: 10.1007/s40820-020-00493-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 06/22/2020] [Indexed: 05/28/2023]
Abstract
The low-dimensional, highly anisotropic geometries, and superior mechanical properties of one-dimensional (1D) nanomaterials allow the exquisite strain engineering with a broad tunability inaccessible to bulk or thin-film materials. Such capability enables unprecedented possibilities for probing intriguing physics and materials science in the 1D limit. Among the techniques for introducing controlled strains in 1D materials, nanoimprinting with embossed substrates attracts increased attention due to its capability to parallelly form nanomaterials into wrinkled structures with controlled periodicities, amplitudes, orientations at large scale with nanoscale resolutions. Here, we systematically investigated the strain-engineered anisotropic optical properties in Te nanowires through introducing a controlled strain field using a resist-free thermally assisted nanoimprinting process. The magnitude of induced strains can be tuned by adjusting the imprinting pressure, the nanowire diameter, and the patterns on the substrates. The observed Raman spectra from the chiral-chain lattice of 1D Te reveal the strong lattice vibration response under the strain. Our results suggest the potential of 1D Te as a promising candidate for flexible electronics, deformable optoelectronics, and wearable sensors. The experimental platform can also enable the exquisite mechanical control in other nanomaterials using substrate-induced, on-demand, and controlled strains.
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Affiliation(s)
- Yixiu Wang
- School of Industrial Engineering, Purdue University, West Lafayette, IN, 47907, USA
- Flex Laboratory, Purdue University, West Lafayette, IN, 47907, USA
| | - Shengyu Jin
- School of Industrial Engineering, Purdue University, West Lafayette, IN, 47907, USA
- Flex Laboratory, Purdue University, West Lafayette, IN, 47907, USA
| | - Qingxiao Wang
- Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Min Wu
- School of Industrial Engineering, Purdue University, West Lafayette, IN, 47907, USA
- Flex Laboratory, Purdue University, West Lafayette, IN, 47907, USA
| | - Shukai Yao
- School of Materials Engineering, Purdue University, West Lafayette, IN, 47907, USA
| | - Peilin Liao
- School of Materials Engineering, Purdue University, West Lafayette, IN, 47907, USA
| | - Moon J Kim
- Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Gary J Cheng
- School of Industrial Engineering, Purdue University, West Lafayette, IN, 47907, USA.
- Flex Laboratory, Purdue University, West Lafayette, IN, 47907, USA.
| | - Wenzhuo Wu
- School of Industrial Engineering, Purdue University, West Lafayette, IN, 47907, USA.
- Flex Laboratory, Purdue University, West Lafayette, IN, 47907, USA.
- Birck Nanotechnology Center, Purdue University, West Lafayette, IN, 47907, USA.
- Regenstrief Center for Healthcare Engineering, Purdue University, West Lafayette, IN, 47907, USA.
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12
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Wei B, Deng Q, Ji Y, Wang Z, Han X. Tunable Mechanical Property and Structural Transition of Silicon Nitride Nanowires Induced by Focused Ion Beam Irradiation. ACS APPLIED MATERIALS & INTERFACES 2020; 12:32175-32181. [PMID: 32551486 DOI: 10.1021/acsami.0c07737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Tailoring mechanical properties of the nanowire (NW) with intricate composite structure helps to design nanodevices with novel functionalities. Here, we performed in situ tensile deformation electron microscopy for the evaluation of the mechanical properties of the focused ion beam (FIB) irradiated silicon nitride (Si3N4) nanowires (NWs). Young's modulus of the FIB-fabricated NWs was mediated between the range of 522 and 65 GPa by modifying the shell thickness of the core-shell structure. The ion-beam-induced amorphization is found to induce the structural transition from an utter crystalline state to a composite NW with an amorphous shell, which results in a brittle-to-ductile transition and an unexpected plastic deformation. These results have practical implications for optimizing nanostructures with the desired mechanical properties, which are of fundamental relevance in designing and fabricating nanomechanical devices.
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Affiliation(s)
- Bin Wei
- School of Materials, Sun Yat-sen University, Guangzhou 510275, China
- International Iberian Nanotechnology Laboratory (INL), Avenida Mestre José Veiga, Braga 4715-330, Portugal
| | - Qingsong Deng
- Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124, China
| | - Yuan Ji
- Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124, China
| | - Zhongchang Wang
- International Iberian Nanotechnology Laboratory (INL), Avenida Mestre José Veiga, Braga 4715-330, Portugal
| | - Xiaodong Han
- Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124, China
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13
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Zhang J, Wang Z, Wang Z, Zhang T, Wei L. In-Fiber Production of Laser-Structured Stress-Mediated Semiconductor Particles. ACS APPLIED MATERIALS & INTERFACES 2019; 11:45330-45337. [PMID: 31701743 DOI: 10.1021/acsami.9b16618] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The ability to generate stressed semiconductor particles is of great importance in the development of tunable semiconductor and photonic devices. However, existing methods including both bottom-up synthesis and top-down fabrication for producing semiconductor particles are inherently free of stress effects. Here, we report a simple approach to generate controllable stress effects on both encapsulated and free-standing semiconductor particles using laser-structured in-fiber materials engineering. The physical mechanism of thermally induced in-fiber built-in stress is investigated, and the feasibility of precisely tuning the stress state during the particle formation is experimentally demonstrated by controlling the laser treatment. Gigapascal-level built-in stress, which is a sufficiently strong stimulus to enable inelastic deformations on the fabricated semiconductor particles, has been achieved via this approach. Both encapsulated and free-standing stressed semiconductor particles are generated for a wide range of in-fiber and out-fiber optoelectronic and biomedical applications.
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Affiliation(s)
- Jing Zhang
- School of Electrical and Electronic Engineering , Nanyang Technological University , 50 Nanyang Avenue , Singapore 639798 , Singapore
| | - Zhe Wang
- School of Electrical and Electronic Engineering , Nanyang Technological University , 50 Nanyang Avenue , Singapore 639798 , Singapore
| | - Zhixun Wang
- School of Electrical and Electronic Engineering , Nanyang Technological University , 50 Nanyang Avenue , Singapore 639798 , Singapore
| | - Ting Zhang
- School of Electrical and Electronic Engineering , Nanyang Technological University , 50 Nanyang Avenue , Singapore 639798 , Singapore
- Institute of Engineering Thermophysics , Chinese Academy of Sciences , Beijing 100190 , China
| | - Lei Wei
- School of Electrical and Electronic Engineering , Nanyang Technological University , 50 Nanyang Avenue , Singapore 639798 , Singapore
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14
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Lin G, Liang D, Yu C, Hong H, Mao Y, Li C, Chen S. Broadband 400-2400 nm Ge heterostructure nanowire photodetector fabricated by three-dimensional Ge condensation technique. OPTICS EXPRESS 2019; 27:32801-32809. [PMID: 31684485 DOI: 10.1364/oe.27.032801] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 10/17/2019] [Indexed: 06/10/2023]
Abstract
A 2.7% tensile strained Ge/SiGe heterostructure nanowire (NW) is in-situ fabricated by a three-dimensional Ge condensation method. The NW metal-semiconductor-metal (MSM) photodetector demonstrates an ultra-broadband detection wavelength of 400-2400 nm, showing a high responsivity of >3.46×102 A/W with a photocurrent gain of >4.32×102 at 1550 nm under -2 V. A high normalized photocurrent to dark current ratio (NPDR) of 1.88×1011 W-1 at 1550 nm under -1 V is achieved. The fully complementary metal-oxide-semiconductor (CMOS) compatible, simple and scalable process suggest that the Ge heterostructure NW is promising for low cost, high performance near-infrared or short wavelength infrared focal plane array applications.
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15
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Interdiffusion in group IV semiconductor material systems: applications, research methods and discoveries. Sci Bull (Beijing) 2019; 64:1436-1455. [PMID: 36659702 DOI: 10.1016/j.scib.2019.07.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 04/15/2019] [Accepted: 06/26/2019] [Indexed: 01/21/2023]
Abstract
Group IV semiconductor alloys and heterostructures such as SiGe, GeSn, Ge/Si and SiGe:C have been widely used and under extensive research for applications in major microelectronic and photonic devices. In the growth and processing of these materials, nanometer scale interdiffusion is common, which is generally undesirable for device performance. With higher Ge molar fractions and higher compressive strains, Si-Ge interdiffusion can be much faster than dopant diffusion. However, Si-Ge interdiffusion behaviors have not been well understood until recent years. Much less studies are available for GeSn. This review starts with basic properties and the applications of major group IV semiconductors, and then reviews the progress made so far on Si-Ge and Ge-Sn interdiffusion behaviors. Theories, experimental methods, design and practical considerations are discussed together with the key findings in this field.
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Abstract
Germanium has long been regarded as a promising laser material for silicon based opto-electronics. It is CMOS-compatible and has a favourable band structure, which can be tuned by strain or alloying with Sn to become direct, as it was found to be required for interband semiconductor lasers. Here, we report lasing in the mid-infrared region (from λ = 3.20 μm up to λ = 3.66 μm) in tensile strained Ge microbridges uniaxially loaded above 5.4% up to 5.9% upon optical pumping, with a differential quantum efficiency close to 100% with a lower bound of 50% and a maximal operating temperature of 100 K. We also demonstrate the effect of a non-equilibrium electron distribution in k-space which reveals the importance of directness for lasing. With these achievements the strained Ge approach is shown to compare well to GeSn, in particular in terms of efficiency. Germanium (based) lasers are a promising route towards a fully CMOS-compatible light source, key to the further development of silicon photonics. Here, the authors realize lasing from strained germanium microbridges up to 100 K, finding a quantum efficiency close to 100%.
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Neupane GP, Zhou K, Chen S, Yildirim T, Zhang P, Lu Y. In-Plane Isotropic/Anisotropic 2D van der Waals Heterostructures for Future Devices. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1804733. [PMID: 30714302 DOI: 10.1002/smll.201804733] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 12/27/2018] [Indexed: 06/09/2023]
Abstract
Mono- to few-layers of 2D semiconducting materials have uniquely inherent optical, electronic, and magnetic properties that make them ideal for probing fundamental scientific phenomena up to the 2D quantum limit and exploring their emerging technological applications. This Review focuses on the fundamental optoelectronic studies and potential applications of in-plane isotropic/anisotropic 2D semiconducting heterostructures. Strong light-matter interaction, reduced dimensionality, and dielectric screening in mono- to few-layers of 2D semiconducting materials result in strong many-body interactions, leading to the formation of robust quasiparticles such as excitons, trions, and biexcitons. An in-plane isotropic nature leads to the quasi-2D particles, whereas, an anisotropic nature leads to quasi-1D particles. Hence, in-plane isotropic/anisotropic 2D heterostructures lead to the formation of quasi-1D/2D particle systems allowing for the manipulation of high binding energy quasi-1D particle populations for use in a wide variety of applications. This Review emphasizes an exciting 1D-2D particles dynamic in such heterostructures and their potential for high-performance photoemitters and exciton-polariton lasers. Moreover, their scopes are also broadened in thermoelectricity, piezoelectricity, photostriction, energy storage, hydrogen evolution reactions, and chemical sensor fields. The unique in-plane isotropic/anisotropic 2D heterostructures may open the possibility of engineering smart devices in the nanodomain with complex opto-electromechanical functions.
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Affiliation(s)
- Guru Prakash Neupane
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518052, Guangdong, China
- Research School of Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, ACT, 2601, Australia
| | - Kai Zhou
- College of Mechatronics and Control Engineering, Shenzhen University, Nan-hai Ave 3688, Shenzhen, 518060, Guangdong, China
| | - Songsong Chen
- College of Mechatronics and Control Engineering, Shenzhen University, Nan-hai Ave 3688, Shenzhen, 518060, Guangdong, China
| | - Tanju Yildirim
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518052, Guangdong, China
| | - Peixin Zhang
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518052, Guangdong, China
| | - Yuerui Lu
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518052, Guangdong, China
- Research School of Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, ACT, 2601, Australia
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18
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Al-Attili AZ, Burt D, Li Z, Higashitarumizu N, Gardes FY, Oda K, Ishikawa Y, Saito S. Germanium vertically light-emitting micro-gears generating orbital angular momentum. OPTICS EXPRESS 2018; 26:34675-34688. [PMID: 30650888 DOI: 10.1364/oe.26.034675] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 11/11/2018] [Indexed: 06/09/2023]
Abstract
Germanium (Ge) is capturing researchers' interest as a possible optical gain medium implementable on complementary metal-oxide-semiconductor (CMOS) chips. Band-gap engineering techniques, relying mainly on tensile strain, are required to overcome the indirect band-gap nature of bulk Ge and promote electron injection into the direct-gap valley. We used Ge on silicon on insulator (Ge-on-SOI) wafers with a high-crystalline-quality Ge layer to fabricate Ge micro-gears on silicon (Si) pillars. Micro-gears are created by etching a periodic grating-like pattern on the circumference of a conventional micro-disk, resulting in a gear shape. Thermal built-in stresses within the SiO2 layers that encapsulate the micro-gears were used to impose tensile strain on Ge. Biaxial tensile strain values ranging from 0.3-0.5% are estimated based on Raman spectroscopy measurements and finite-element method (FEM) simulations. Multiple sharp-peak resonances within the Ge direct-gap were detected at room temperature by photo-luminescence (PL) measurements. By investigating the micro-gears spectrum using finite-difference time-domain (FDTD) simulations, we identified vertically emitted optical modes with non-zero orbital angular momentum (OAM). To our best knowledge, this is the first demonstration of OAM generation within a Ge light source.
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Qi Z, Sun H, Luo M, Jung Y, Nam D. Strained germanium nanowire optoelectronic devices for photonic-integrated circuits. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:334004. [PMID: 29968583 DOI: 10.1088/1361-648x/aad0c0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Strained germanium nanowires have recently become an important material of choice for silicon-compatible optoelectronic devices. While the indirect bandgap nature of germanium had long been problematic both in light absorption and emission, recent successful demonstrations of bandstructure engineering by elastic strain have opened up the possibility of achieving direct bandgap in germanium, paving the way towards the realization of various high-performance optical devices integrated on a silicon platform. In particular, the latest demonstration of a low-threshold optically pumped laser in a highly strained germanium nanowire is expected to vitalize the field of silicon photonics further. Here, we review recent advances and challenges in strained germanium nanowires for optoelectronic applications such as photodetectors and lasers. We firstly introduce the theoretical foundation behind strained germanium nanowire optoelectronics. And several practical approaches that have been proposed to apply tensile strain in germanium nanowires are further discussed. Then we address the latest progress in the developments of strained germanium nanowire optoelectronic devices. Finally, we discuss the implications of these experimental achievements and the future outlook in this promising research field.
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Affiliation(s)
- Zhipeng Qi
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore, Singapore
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20
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Ghadimi AH, Fedorov SA, Engelsen NJ, Bereyhi MJ, Schilling R, Wilson DJ, Kippenberg TJ. Elastic strain engineering for ultralow mechanical dissipation. Science 2018; 360:764-768. [DOI: 10.1126/science.aar6939] [Citation(s) in RCA: 168] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 03/28/2018] [Indexed: 01/20/2023]
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21
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Im H, Park K, Kim J, Kim D, Lee J, Lee JA, Park J, Ahn JP. Strain Mapping and Raman Spectroscopy of Bent GaP and GaAs Nanowires. ACS OMEGA 2018; 3:3129-3135. [PMID: 31458573 PMCID: PMC6641494 DOI: 10.1021/acsomega.8b00063] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 02/21/2018] [Indexed: 06/09/2023]
Abstract
Strain engineering of nanowires (NWs) has been recognized as a powerful strategy for tuning the optical and electronic properties of nanoscale semiconductors. Therefore, the characterization of the strains with nanometer-scale spatial resolution is of great importance for various promising applications. In the present work, we synthesized single-crystalline zinc blende phase GaP and GaAs NWs using the chemical vapor transport method and visualized their bending strains (up to 3%) with high precision using the nanobeam electron diffraction technique. The strain mapping at all crystallographic axes revealed that (i) maximum strain exists along the growth direction ([111]) with the tensile and compressive strains at the outer and inner parts, respectively; (ii) the opposite strains appeared along the perpendicular direction ([2̅11]); and (iii) the tensile strain was larger than the coexisting compressive strain at all axes. The Raman spectrum collected for individual bent NWs showed the peak broadening and red shift of the transverse optical modes that were well-correlated with the strain maps. These results are consistent with the larger mechanical modulus of GaP than that of GaAs. Our work provides new insight into the bending strain of III-V semiconductors, which is of paramount importance in the performance of flexible or bendable electronics.
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Affiliation(s)
- Hyung
Soon Im
- Department
of Chemistry, Korea University, Sejong 30019, Korea
| | - Kidong Park
- Department
of Chemistry, Korea University, Sejong 30019, Korea
| | - Jundong Kim
- Department
of Chemistry, Korea University, Sejong 30019, Korea
| | - Doyeon Kim
- Department
of Chemistry, Korea University, Sejong 30019, Korea
| | - Jinha Lee
- Department
of Chemistry, Korea University, Sejong 30019, Korea
| | - Jung Ah Lee
- Department
of Chemistry, Korea University, Sejong 30019, Korea
| | - Jeunghee Park
- Department
of Chemistry, Korea University, Sejong 30019, Korea
| | - Jae-Pyoung Ahn
- Korea
Advanced Analysis Center, Korea Institute
of Science and Technology, Seoul 136-791, Korea
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22
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Pial TH, Rakib T, Mojumder S, Motalab M, Akanda MAS. Atomistic investigations on the mechanical properties and fracture mechanisms of indium phosphide nanowires. Phys Chem Chem Phys 2018. [PMID: 29536996 DOI: 10.1039/c7cp08252e] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The mechanical properties of indium phosphide (InP) nanowires are an emerging issue due to the promising applications of these nanowires in nanoelectromechanical and microelectromechanical devices. In this study, molecular dynamics simulations of zincblende (ZB) and wurtzite (WZ) crystal structured InP nanowires (NWs) are presented under uniaxial tension at varying sizes and temperatures. It is observed that the tensile strengths of both types of NWs show inverse relationships with temperature, but are independent of the size of the nanowires. Moreover, applied load causes brittle fracture by nucleating cleavage on ZB and WZ NWs. When the tensile load is applied along the [001] direction, the direction of the cleavage planes of ZB NWs changes with temperature. It is found that the {111} planes are the cleavage planes at lower temperatures; on the other hand, the {110} cleavage planes are activated at elevated temperatures. In the case of WZ NWs, fracture of the material is observed to occur by cleaving along the (0001) plane irrespective of temperature when the tensile load is applied along the [0001] direction. Furthermore, the WZ NWs of InP show considerably higher strength than their ZB counterparts. Finally, the impact of strain rate on the failure behavior of InP NWs is also studied, and higher fracture strengths and strains at higher strain rates are found. With increasing strain rate, the number of cleavages also increases in the NWs. This paper also provides in-depth understanding of the failure behavior of InP NWs, which will aid the design of efficient InP NWs-based devices.
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Affiliation(s)
- Turash Haque Pial
- Department of Mechanical Engineering, Bangladesh University of Engineering and Technology, Dhaka-1000, Bangladesh.
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23
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Chen Y, Zhang Y, Keil R, Zopf M, Ding F, Schmidt OG. Temperature-Dependent Coercive Field Measured by a Quantum Dot Strain Gauge. NANO LETTERS 2017; 17:7864-7868. [PMID: 29131635 DOI: 10.1021/acs.nanolett.7b04138] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Coercive fields of piezoelectric materials can be strongly influenced by environmental temperature. We investigate this influence using a heterostructure consisting of a single crystal piezoelectric film and a quantum dots containing membrane. Applying electric field leads to a physical deformation of the piezoelectric film, thereby inducing strain in the quantum dots and thus modifying their optical properties. The wavelength of the quantum dot emission shows butterfly-like loops, from which the coercive fields are directly derived. The results suggest that coercive fields at cryogenic temperatures are strongly increased, yielding values several tens of times larger than those at room temperature. We adapt a theoretical model to fit the measured data with very high agreement. Our work provides an efficient framework for predicting the properties of ferroelectric materials and advocating their practical applications, especially at low temperatures.
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Affiliation(s)
- Yan Chen
- Institute for Integrative Nanosciences, IFW Dresden , Helmholtzstraße 20, 01069 Dresden, Germany
| | - Yang Zhang
- Institute for Integrative Nanosciences, IFW Dresden , Helmholtzstraße 20, 01069 Dresden, Germany
| | - Robert Keil
- Institute for Integrative Nanosciences, IFW Dresden , Helmholtzstraße 20, 01069 Dresden, Germany
| | - Michael Zopf
- Institute for Integrative Nanosciences, IFW Dresden , Helmholtzstraße 20, 01069 Dresden, Germany
| | - Fei Ding
- Institute for Integrative Nanosciences, IFW Dresden , Helmholtzstraße 20, 01069 Dresden, Germany
- Institut für Festkörperphysik, Leibniz Universität Hannover , Appelstraße 2, 30167 Hannover, Germany
| | - Oliver G Schmidt
- Institute for Integrative Nanosciences, IFW Dresden , Helmholtzstraße 20, 01069 Dresden, Germany
- Chemnitz University of Technology , Reichenhainerstraße 70, 09107 Chemnitz, Germany
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24
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Low-threshold optically pumped lasing in highly strained germanium nanowires. Nat Commun 2017; 8:1845. [PMID: 29184064 PMCID: PMC5705600 DOI: 10.1038/s41467-017-02026-w] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 11/02/2017] [Indexed: 11/09/2022] Open
Abstract
The integration of efficient, miniaturized group IV lasers into CMOS architecture holds the key to the realization of fully functional photonic-integrated circuits. Despite several years of progress, however, all group IV lasers reported to date exhibit impractically high thresholds owing to their unfavourable bandstructures. Highly strained germanium with its fundamentally altered bandstructure has emerged as a potential low-threshold gain medium, but there has yet to be a successful demonstration of lasing from this seemingly promising material system. Here we demonstrate a low-threshold, compact group IV laser that employs a germanium nanowire under a 1.6% uniaxial tensile strain as the gain medium. The amplified material gain in strained germanium can sufficiently overcome optical losses at 83 K, thus allowing the observation of multimode lasing with an optical pumping threshold density of ~3.0 kW cm-2. Our demonstration opens new possibilities for group IV lasers for photonic-integrated circuits.
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25
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Park JM, Cho JH, Ha JH, Kim HS, Kim SW, Lee J, Chung KY, Cho BW, Choi HJ. Reversible crystalline-amorphous phase transformation in Si nanosheets with lithi-/delithiation. NANOTECHNOLOGY 2017; 28:255401. [PMID: 28548050 DOI: 10.1088/1361-6528/aa6dad] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Silicon (Si) has a large theoretical capacity of 4200 mAhg-1 and has great potential as a high-performance anode material for Li ion batteries (LIBs). Meanwhile, nanostructures can exploit the potential of Si and, accordingly, many zero-dimensional (0D) and one-dimensional (1D) Si nanostructures have been studied. Herein, we report on two-dimensional (2D) Si nanostructures, Si nanosheets (SiNSs), as anodes for LIBs. These 2D Si nanostructures, with a thickness as low 5 nm and widths of several micrometers, show reversible crystalline-amorphous phase transformations with the lithi-/delithiation by the dimensionality of morphology and large surface area. The reversible crystalline-amorphous phase transformation provides a structural stability of Li+ insertions and makes SiNSs promising candidates for reliable high-performance LIBs anode materials.
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Affiliation(s)
- Jeong Min Park
- Global E3 Institute and Department of Materials Science and Engineering, Yonsei University, Seoul 120-749, Republic of Korea. Energy Convergence Research Center, Korea Institute of Science and Technology, Seoul 130-650, Republic of Korea
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26
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Tardif S, Gassenq A, Guilloy K, Pauc N, Osvaldo Dias G, Hartmann JM, Widiez J, Zabel T, Marin E, Sigg H, Faist J, Chelnokov A, Reboud V, Calvo V, Micha JS, Robach O, Rieutord F. Lattice strain and tilt mapping in stressed Ge microstructures using X-ray Laue micro-diffraction and rainbow filtering. J Appl Crystallogr 2016. [DOI: 10.1107/s1600576716010347] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Laue micro-diffraction and simultaneous rainbow-filtered micro-diffraction were used to measure accurately the full strain tensor and the lattice orientation distribution at the sub-micrometre scale in highly strained, suspended Ge micro-devices. A numerical approach to obtain the full strain tensor from the deviatoric strain measurement alone is also demonstrated and used for faster full strain mapping. The measurements were performed in a series of micro-devices under either uniaxial or biaxial stress and an excellent agreement with numerical simulations was found. This shows the superior potential of Laue micro-diffraction for the investigation of highly strained micro-devices.
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27
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Petykiewicz J, Nam D, Sukhdeo DS, Gupta S, Buckley S, Piggott AY, Vučković J, Saraswat KC. Direct Bandgap Light Emission from Strained Germanium Nanowires Coupled with High-Q Nanophotonic Cavities. NANO LETTERS 2016; 16:2168-2173. [PMID: 26907359 DOI: 10.1021/acs.nanolett.5b03976] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A silicon-compatible light source is the final missing piece for completing high-speed, low-power on-chip optical interconnects. In this paper, we present a germanium nanowire light emitter that encompasses all the aspects of potential low-threshold lasers: highly strained germanium gain medium, strain-induced pseudoheterostructure, and high-Q nanophotonic cavity. Our nanowire structure presents greatly enhanced photoluminescence into cavity modes with measured quality factors of up to 2000. By varying the dimensions of the germanium nanowire, we tune the emission wavelength over more than 400 nm with a single lithography step. We find reduced optical loss in optical cavities formed with germanium under high (>2.3%) tensile strain. Our compact, high-strain cavities open up new possibilities for low-threshold germanium-based lasers for on-chip optical interconnects.
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Affiliation(s)
- Jan Petykiewicz
- Department of Electrical Engineering, Stanford University , Stanford, California 94305, United States
| | - Donguk Nam
- Department of Electronic Engineering, Inha University , Incheon 402-751, South Korea
| | - David S Sukhdeo
- Department of Electrical Engineering, Stanford University , Stanford, California 94305, United States
| | - Shashank Gupta
- Department of Electrical Engineering, Stanford University , Stanford, California 94305, United States
| | - Sonia Buckley
- Department of Electrical Engineering, Stanford University , Stanford, California 94305, United States
| | - Alexander Y Piggott
- Department of Electrical Engineering, Stanford University , Stanford, California 94305, United States
| | - Jelena Vučković
- Department of Electrical Engineering, Stanford University , Stanford, California 94305, United States
| | - Krishna C Saraswat
- Department of Electrical Engineering, Stanford University , Stanford, California 94305, United States
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28
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Virgilio M, Grosso G. Strain-modulated Ge superlattices. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:485305. [PMID: 26569138 DOI: 10.1088/0953-8984/27/48/485305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We present a numerical study of the electronic and optical properties of a model single-element superlattice made of a periodic sequence of relaxed and strained regions of a germanium crystal, realized by means of an externally applied strain. We adopt the tight-binding model to evaluate the strain-driven modifications of the band structure and the optical properties. Superlattice band gaps, spatial confinement of near-gap valence and conduction states, and analysis of their symmetry character, have been obtained for different superlattice periodicities and strain intensities. Our results indicate that, for suitable choices of spatial periodicity and strain values, type-I and direct-gap superlattices, with strong dipole matrix elements, can be realized. Conceptually, we demonstrate that Ge single-element strained superlattices could be active materials for novel Si-compatible optical devices.
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Affiliation(s)
- Michele Virgilio
- Dipartimento di Fisica 'E Fermi', Università di Pisa, Largo Pontecorvo 3, I-56127 Pisa, Italy. NEST, Istituto Nanoscienze-CNR, P.za San Silvestro 12, I-56127 Pisa, Italy
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29
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Hauge HIT, Verheijen MA, Conesa-Boj S, Etzelstorfer T, Watzinger M, Kriegner D, Zardo I, Fasolato C, Capitani F, Postorino P, Kölling S, Li A, Assali S, Stangl J, Bakkers EPAM. Hexagonal Silicon Realized. NANO LETTERS 2015; 15:5855-60. [PMID: 26230363 DOI: 10.1021/acs.nanolett.5b01939] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Silicon, arguably the most important technological semiconductor, is predicted to exhibit a range of new and interesting properties when grown in the hexagonal crystal structure. To obtain pure hexagonal silicon is a great challenge because it naturally crystallizes in the cubic structure. Here, we demonstrate the fabrication of pure and stable hexagonal silicon evidenced by structural characterization. In our approach, we transfer the hexagonal crystal structure from a template hexagonal gallium phosphide nanowire to an epitaxially grown silicon shell, such that hexagonal silicon is formed. The typical ABABAB... stacking of the hexagonal structure is shown by aberration-corrected imaging in transmission electron microscopy. In addition, X-ray diffraction measurements show the high crystalline purity of the material. We show that this material is stable up to 9 GPa pressure. With this development, we open the way for exploring its optical, electrical, superconducting, and mechanical properties.
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Affiliation(s)
| | - Marcel A Verheijen
- Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
- Philips Innovation Services, 5656 AE Eindhoven, The Netherlands
| | - Sonia Conesa-Boj
- Kavli Institute of Nanoscience, Delft University of Technology , 2600 GA Delft, The Netherlands
| | - Tanja Etzelstorfer
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz , A-4040 Linz, Austria
| | - Marc Watzinger
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz , A-4040 Linz, Austria
| | - Dominik Kriegner
- Department of Condensed Matter Physics, Charles University in Prague , Ke Karlovu 5, 121 16 Prague 2, Czech Republic
| | - Ilaria Zardo
- Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - Claudia Fasolato
- CNR-IOM and Dipartimento di Fisica, Università di Roma Sapienza , Piazzale le Aldo Moro 5, I-00185 Rome, Italy
- Center for Life Nanoscience@Sapienza, Istituto Italiano di Tecnologia , V.le Regina Elena, 291-00185, Rome, Italy
| | - Francesco Capitani
- CNR-IOM and Dipartimento di Fisica, Università di Roma Sapienza , Piazzale le Aldo Moro 5, I-00185 Rome, Italy
| | - Paolo Postorino
- CNR-IOM and Dipartimento di Fisica, Università di Roma Sapienza , Piazzale le Aldo Moro 5, I-00185 Rome, Italy
- Center for Life Nanoscience@Sapienza, Istituto Italiano di Tecnologia , V.le Regina Elena, 291-00185, Rome, Italy
| | - Sebastian Kölling
- Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - Ang Li
- Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - Simone Assali
- Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - Julian Stangl
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz , A-4040 Linz, Austria
| | - Erik P A M Bakkers
- Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology , 2600 GA Delft, The Netherlands
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30
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Sukhdeo DS, Nam D, Kang JH, Brongersma ML, Saraswat KC. Bandgap-customizable germanium using lithographically determined biaxial tensile strain for silicon-compatible optoelectronics. OPTICS EXPRESS 2015; 23:16740-16749. [PMID: 26191686 DOI: 10.1364/oe.23.016740] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Strain engineering has proven to be vital for germanium-based photonics, in particular light emission. However, applying a large permanent biaxial tensile strain to germanium has been a challenge. We present a simple, CMOS-compatible technique to conveniently induce a large, spatially homogenous strain in circular structures patterned within germanium nanomembranes. Our technique works by concentrating and amplifying a pre-existing small strain into a circular region. Biaxial tensile strains as large as 1.11% are observed by Raman spectroscopy and are further confirmed by photoluminescence measurements, which show enhanced and redshifted light emission from the strained germanium. Our technique allows the amount of biaxial strain to be customized lithographically, allowing the bandgaps of different germanium structures to be independently customized in a single mask process.
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31
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Watanabe K, Nagata T, Wakayama Y, Sekiguchi T, Erdélyi R, Volk J. Band-gap deformation potential and elasticity limit of semiconductor free-standing nanorods characterized in situ by scanning electron microscope-cathodoluminescence nanospectroscopy. ACS NANO 2015; 9:2989-3001. [PMID: 25689728 DOI: 10.1021/nn507159u] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Modern field-effect transistors or laser diodes take advantages of band-edge structures engineered by large uniaxial strain εzz, available up to an elasticity limit at a rate of band-gap deformation potential azz (= dEg/dεzz). However, contrary to aP values under hydrostatic pressure, there is no quantitative consensus on azz values under uniaxial tensile, compressive, and bending stress. This makes band-edge engineering inefficient. Here we propose SEM-cathodoluminescence nanospectroscopy under in situ nanomanipulation (Nanoprobe-CL). An apex of a c-axis-oriented free-standing ZnO nanorod (NR) is deflected by point-loading of bending stress, where local uniaxial strain (εcc = r/R) and its gradient across a NR (dεcc/dr = R(-1)) are controlled by a NR local curvature (R(-1)). The NR elasticity limit is evaluated sequentially (εcc = 0.04) from SEM observation of a NR bending deformation cycle. An electron beam is focused on several spots crossing a bent NR, and at each spot the local Eg is evaluated from near-band-edge CL emission energy. Uniaxial acc (= dEg/dεcc) is evaluated at regulated surface depth, and the impact of R(-1) on observed acc is investigated. The acc converges with -1.7 eV to the R(-1) = 0 limit, whereas it quenches with increasing R(-1), which is attributed to free-exciton drift under transversal band-gap gradient. Surface-sensitive CL measurements suggest that a discrepancy from bulk acc = -4 eV may originate from strain relaxation at the side surface under uniaxial stress. The nanoprobe-CL technique reveals an Eg(εij) response to specific strain tensor εij (i, j = x, y, z) and strain-gradient effects on a minority carrier population, enabling simulations and strain-dependent measurements of nanodevices with various structures.
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Affiliation(s)
- Kentaro Watanabe
- †WPI Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
- ‡Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8571, Japan
| | - Takahiro Nagata
- †WPI Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Yutaka Wakayama
- †WPI Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Takashi Sekiguchi
- †WPI Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Róbert Erdélyi
- §MTA EK Institute of Technical Physics and Materials Science, Konkoly Thege M. út 29-33, 1121 Budapest, Hungary
| | - János Volk
- §MTA EK Institute of Technical Physics and Materials Science, Konkoly Thege M. út 29-33, 1121 Budapest, Hungary
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Guo Z, Li H, Zhou L, Zhao D, Wu Y, Zhang Z, Zhang W, Li C, Yao J. Large-scale horizontally aligned ZnO microrod arrays with controlled orientation, periodic distribution as building blocks for chip-in piezo-phototronic LEDs. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2015; 11:438-445. [PMID: 25223456 DOI: 10.1002/smll.201402151] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Indexed: 06/03/2023]
Abstract
A novel method of fabricating large-scale horizontally aligned ZnO microrod arrays with controlled orientation and periodic distribution via combing technology is introduced. Horizontally aligned ZnO microrod arrays with uniform orientation and periodic distribution can be realized based on the conventional bottom-up method prepared vertically aligned ZnO microrod matrix via the combing method. When the combing parameters are changed, the orientation of horizontally aligned ZnO microrod arrays can be adjusted (θ = 90° or 45°) in a plane and a misalignment angle of the microrods (0.3° to 2.3°) with low-growth density can be obtained. To explore the potential applications based on the vertically and horizontally aligned ZnO microrods on p-GaN layer, piezo-phototronic devices such as heterojunction LEDs are built. Electroluminescence (EL) emission patterns can be adjusted for the vertically and horizontally aligned ZnO microrods/p-GaN heterojunction LEDs by applying forward bias. Moreover, the emission color from UV-blue to yellow-green can be tuned by investigating the piezoelectric properties of the materials. The EL emission mechanisms of the LEDs are discussed in terms of band diagrams of the heterojunctions and carrier recombination processes.
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Affiliation(s)
- Zhen Guo
- Key Lab of Bio-Medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, No.88-Keling Road, Suzhou New District, 215163, PR China
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33
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Balois MV, Hayazawa N, Tarun A, Kawata S, Reiche M, Moutanabbir O. Direct optical mapping of anisotropic stresses in nanowires using transverse optical phonon splitting. NANO LETTERS 2014; 14:3793-3798. [PMID: 24867226 DOI: 10.1021/nl500891f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Strain engineering is ubiquitous in the design and fabrication of innovative, high-performance electronic, optoelectronic, and photovoltaic devices. The increasing importance of strain-engineered nanoscale materials has raised significant challenges at both fabrication and characterization levels. Raman scattering spectroscopy (RSS) is one of the most straightforward techniques that have been broadly utilized to estimate the strain in semiconductors. However, this technique is incapable of measuring the individual components of stress, thus only providing the average values of the in-plane strain. This inherit limitation severely diminishes the importance of RSS analysis and makes it ineffective in the predominant case of nanostructures and devices with a nonuniform distribution of strain. Herein, we circumvent this major limitation and demonstrate for the first time the application of RSS to simultaneously probe the two local stress in-plane components in individual ultrathin silicon nanowires based on the imaging of the splitting of the two forbidden transverse optical phonons.
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Affiliation(s)
- Maria Vanessa Balois
- Near-field Nanophotonics Research Team, RIKEN, The Institute of Physical and Chemical Research , 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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Murphy KF, Piccione B, Zanjani MB, Lukes JR, Gianola DS. Strain- and defect-mediated thermal conductivity in silicon nanowires. NANO LETTERS 2014; 14:3785-3792. [PMID: 24885097 DOI: 10.1021/nl500840d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The unique thermal transport of insulating nanostructures is attributed to the convergence of material length scales with the mean free paths of quantized lattice vibrations known as phonons, enabling promising next-generation thermal transistors, thermal barriers, and thermoelectrics. Apart from size, strain and defects are also known to drastically affect heat transport when introduced in an otherwise undisturbed crystalline lattice. Here we report the first experimental measurements of the effect of both spatially uniform strain and point defects on thermal conductivity of an individual suspended nanowire using in situ Raman piezothermography. Our results show that whereas phononic transport in undoped Si nanowires with diameters in the range of 170-180 nm is largely unaffected by uniform elastic tensile strain, another means of disturbing a pristine lattice, namely, point defects introduced via ion bombardment, can reduce the thermal conductivity by over 70%. In addition to discerning surface- and core-governed pathways for controlling thermal transport in phonon-dominated insulators and semiconductors, we expect our novel approach to have broad applicability to a wide class of functional one- and two-dimensional nanomaterials.
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Affiliation(s)
- Kathryn F Murphy
- Department of Materials Science and Engineering and ‡Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
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35
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Süess MJ, Minamisawa RA, Geiger R, Bourdelle KK, Sigg H, Spolenak R. Power-dependent Raman analysis of highly strained Si nanobridges. NANO LETTERS 2014; 14:1249-1254. [PMID: 24564181 DOI: 10.1021/nl404152r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Strain analysis of complex three-dimensional nanobridges conducted via Raman spectroscopy requires careful experimentation and data analysis supported by simulations. A method combining micro-Raman spectroscopy with finite element analysis is presented, enabling a detailed understanding of strain-sensitive Raman data measured on Si nanobridges. Power-dependent measurements are required to account for the a priori unknown scattering efficiency related to size and geometry. The experimental data is used to assess the validity of previously published phonon deformation potentials.
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Affiliation(s)
- M J Süess
- Laboratory for Nanometallurgy (LNM), Department of Materials Science, ETH Zurich , CH-8093 Zürich, Switzerland
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36
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Etzelstorfer T, Süess MJ, Schiefler GL, Jacques VLR, Carbone D, Chrastina D, Isella G, Spolenak R, Stangl J, Sigg H, Diaz A. Scanning X-ray strain microscopy of inhomogeneously strained Ge micro-bridges. JOURNAL OF SYNCHROTRON RADIATION 2014; 21:111-8. [PMID: 24365924 PMCID: PMC3874020 DOI: 10.1107/s1600577513025459] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 09/13/2013] [Indexed: 06/03/2023]
Abstract
Strained semiconductors are ubiquitous in microelectronics and microelectromechanical systems, where high local stress levels can either be detrimental for their integrity or enhance their performance. Consequently, local probes for elastic strain are essential in analyzing such devices. Here, a scanning X-ray sub-microprobe experiment for the direct measurement of deformation over large areas in single-crystal thin films with a spatial resolution close to the focused X-ray beam size is presented. By scanning regions of interest of several tens of micrometers at different rocking angles of the sample in the vicinity of two Bragg reflections, reciprocal space is effectively mapped in three dimensions at each scanning position, obtaining the bending, as well as the in-plane and out-of-plane strain components. Highly strained large-area Ge structures with applications in optoelectronics are used to demonstrate the potential of this technique and the results are compared with finite-element-method models for validation.
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Affiliation(s)
- Tanja Etzelstorfer
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Altenbergerstrasse 69, 4040 Linz, Austria
| | - Martin J. Süess
- Electron Microscopy, ETH Zurich, Wolfgang-Pauli-Strasse 16, 8093 Zurich, Switzerland
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
- Laboratory for Nanometallurgy, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich, Switzerland
| | | | - Vincent L. R. Jacques
- European Synchrotron Radiation Facility, 6 rue Jules Horowitz, BP 220, 38043 Grenoble, France
| | - Dina Carbone
- European Synchrotron Radiation Facility, 6 rue Jules Horowitz, BP 220, 38043 Grenoble, France
| | - Daniel Chrastina
- L-NESS, Dipartimento di Fisica del Politecnico di Milano, Polo di Como, 22100 Como, Italy
| | - Giovanni Isella
- L-NESS, Dipartimento di Fisica del Politecnico di Milano, Polo di Como, 22100 Como, Italy
| | - Ralph Spolenak
- Laboratory for Nanometallurgy, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich, Switzerland
| | - Julian Stangl
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Altenbergerstrasse 69, 4040 Linz, Austria
| | - Hans Sigg
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Ana Diaz
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
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Falub CV, Meduňa M, Chrastina D, Isa F, Marzegalli A, Kreiliger T, Taboada AG, Isella G, Miglio L, Dommann A, von Känel H. Perfect crystals grown from imperfect interfaces. Sci Rep 2013; 3:2276. [PMID: 23880632 PMCID: PMC3721082 DOI: 10.1038/srep02276] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 07/09/2013] [Indexed: 11/30/2022] Open
Abstract
The fabrication of advanced devices increasingly requires materials with different properties to be combined in the form of monolithic heterostructures. In practice this means growing epitaxial semiconductor layers on substrates often greatly differing in lattice parameters and thermal expansion coefficients. With increasing layer thickness the relaxation of misfit and thermal strains may cause dislocations, substrate bowing and even layer cracking. Minimizing these drawbacks is therefore essential for heterostructures based on thick layers to be of any use for device fabrication. Here we prove by scanning X-ray nanodiffraction that mismatched Ge crystals epitaxially grown on deeply patterned Si substrates evolve into perfect structures away from the heavily dislocated interface. We show that relaxing thermal and misfit strains result just in lattice bending and tiny crystal tilts. We may thus expect a new concept in which continuous layers are replaced by quasi-continuous crystal arrays to lead to dramatically improved physical properties.
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Affiliation(s)
- Claudiu V Falub
- Laboratory for Solid State Physics, ETH-Zürich, Schafmattstrasse 16, 8093 Zürich, Switzerland.
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Jin Y, Wang N, Yuan B, Sun J, Li M, Zheng W, Zhang W, Jiang X. Stress-induced self-assembly of complex three dimensional structures by elastic membranes. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2013; 9:2410-2414. [PMID: 23776107 DOI: 10.1002/smll.201300929] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2013] [Indexed: 06/02/2023]
Abstract
Based on the stress-induced rolling membrane technique, complex three-dimensional structures are designed, such as tubes with wrinkled walls, tubes-in-a-tube, and spiral structures. Narrow PDMS strips are used instead of the whole PDMS top layer, thus obtaining tubes made of the bottom polymer.
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Affiliation(s)
- Yu Jin
- CAS Key Lab for Biological Effects of Nanomaterials and Nanosafety, National Centre of Nanoscience and Technology, 11 Beiyitiao, Zhongguancun, Haidian District, Beijing 100190, China
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39
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Nam D, Sukhdeo DS, Kang JH, Petykiewicz J, Lee JH, Jung WS, Vučković J, Brongersma ML, Saraswat KC. Strain-induced pseudoheterostructure nanowires confining carriers at room temperature with nanoscale-tunable band profiles. NANO LETTERS 2013; 13:3118-23. [PMID: 23758608 DOI: 10.1021/nl401042n] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Semiconductor heterostructures play a vital role in photonics and electronics. They are typically realized by growing layers of different materials, complicating fabrication and limiting the number of unique heterojunctions on a wafer. In this Letter, we present single-material nanowires which behave exactly like traditional heterostructures. These pseudoheterostructures have electronic band profiles that are custom-designed at the nanoscale by strain engineering. Since the band profile depends only on the nanowire geometry with this approach, arbitrary band profiles can be individually tailored at the nanoscale using existing nanolithography. We report the first experimental observations of spatially confined, greatly enhanced (>200×), and wavelength-shifted (>500 nm) emission from strain-induced potential wells that facilitate effective carrier collection at room temperature. This work represents a fundamentally new paradigm for creating nanoscale devices with full heterostructure behavior in photonics and electronics.
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Affiliation(s)
- Donguk Nam
- Department of Electrical Engineering and ‡Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States
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