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Hofmann EVS, Stock TJZ, Warschkow O, Conybeare R, Curson NJ, Schofield SR. Room Temperature Incorporation of Arsenic Atoms into the Germanium (001) Surface. Angew Chem Int Ed Engl 2023; 62:e202213982. [PMID: 36484458 PMCID: PMC10108107 DOI: 10.1002/anie.202213982] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 11/29/2022] [Accepted: 12/09/2022] [Indexed: 12/13/2022]
Abstract
Germanium has emerged as an exceptionally promising material for spintronics and quantum information applications, with significant fundamental advantages over silicon. However, efforts to create atomic-scale devices using donor atoms as qubits have largely focused on phosphorus in silicon. Positioning phosphorus in silicon with atomic-scale precision requires a thermal incorporation anneal, but the low success rate for this step has been shown to be a fundamental limitation prohibiting the scale-up to large-scale devices. Here, we present a comprehensive study of arsine (AsH3 ) on the germanium (001) surface. We show that, unlike any previously studied dopant precursor on silicon or germanium, arsenic atoms fully incorporate into substitutional surface lattice sites at room temperature. Our results pave the way for the next generation of atomic-scale donor devices combining the superior electronic properties of germanium with the enhanced properties of arsine/germanium chemistry that promises scale-up to large numbers of deterministically placed qubits.
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Affiliation(s)
- Emily V S Hofmann
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK.,Department of Electronic and Electrical Engineering, University College London, London, WC1E 6BT, UK.,IHP Leibniz-Institut für Innovative Mikroelektronik, Im Technologiepark 25, 15236, Frankfurt (Oder), Germany
| | - Taylor J Z Stock
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK.,Department of Electronic and Electrical Engineering, University College London, London, WC1E 6BT, UK
| | - Oliver Warschkow
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK
| | - Rebecca Conybeare
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK.,Department of Physics and Astronomy, University College London, London, WC1E 6BT, UK
| | - Neil J Curson
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK.,Department of Electronic and Electrical Engineering, University College London, London, WC1E 6BT, UK
| | - Steven R Schofield
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK.,Department of Physics and Astronomy, University College London, London, WC1E 6BT, UK
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Scanning Probe Lithography: State-of-the-Art and Future Perspectives. MICROMACHINES 2022; 13:mi13020228. [PMID: 35208352 PMCID: PMC8878409 DOI: 10.3390/mi13020228] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 01/24/2022] [Accepted: 01/28/2022] [Indexed: 02/04/2023]
Abstract
High-throughput and high-accuracy nanofabrication methods are required for the ever-increasing demand for nanoelectronics, high-density data storage devices, nanophotonics, quantum computing, molecular circuitry, and scaffolds in bioengineering used for cell proliferation applications. The scanning probe lithography (SPL) nanofabrication technique is a critical nanofabrication method with great potential to evolve into a disruptive atomic-scale fabrication technology to meet these demands. Through this timely review, we aspire to provide an overview of the SPL fabrication mechanism and the state-the-art research in this area, and detail the applications and characteristics of this technique, including the effects of thermal aspects and chemical aspects, and the influence of electric and magnetic fields in governing the mechanics of the functionalized tip interacting with the substrate during SPL. Alongside this, the review also sheds light on comparing various fabrication capabilities, throughput, and attainable resolution. Finally, the paper alludes to the fact that a majority of the reported literature suggests that SPL has yet to achieve its full commercial potential and is currently largely a laboratory-based nanofabrication technique used for prototyping of nanostructures and nanodevices.
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Jia P, Chen W, Qiao J, Zhang M, Zheng X, Xue Z, Liang R, Tian C, He L, Di Z, Wang X. Programmable graphene nanobubbles with three-fold symmetric pseudo-magnetic fields. Nat Commun 2019; 10:3127. [PMID: 31311927 PMCID: PMC6635427 DOI: 10.1038/s41467-019-11038-7] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 06/11/2019] [Indexed: 11/09/2022] Open
Abstract
Graphene nanobubbles (GNBs) have attracted much attention due to the ability to generate large pseudo-magnetic fields unattainable by ordinary laboratory magnets. However, GNBs are always randomly produced by the reported protocols, therefore, their size and location are difficult to manipulate, which restricts their potential applications. Here, using the functional atomic force microscopy (AFM), we demonstrate the ability to form programmable GNBs. The precision of AFM facilitates the location definition of GNBs, and their size and shape are tuned by the stimulus bias of AFM tip. With tuning the tip voltage, the bubble contour can gradually transit from parabolic to Gaussian profile. Moreover, the unique three-fold symmetric pseudo-magnetic field pattern with monotonous regularity, which is only theoretically predicted previously, is directly observed in the GNB with an approximately parabolic profile. Our study may provide an opportunity to study high magnetic field regimes with the designed periodicity in two dimensional materials.
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Affiliation(s)
- Pengfei Jia
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 200050, Shanghai, China.,Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Wenjing Chen
- The Center for Advanced Quantum Studies, Department of Physics, Beijing Normal University, 100875, Beijing, China
| | - Jiabin Qiao
- The Center for Advanced Quantum Studies, Department of Physics, Beijing Normal University, 100875, Beijing, China
| | - Miao Zhang
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 200050, Shanghai, China
| | - Xiaohu Zheng
- International Center for Quantum Materials, Peking University, 100871, Beijing, China
| | - Zhongying Xue
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 200050, Shanghai, China
| | - Rongda Liang
- Department of Physics, State Key Laboratory of Surface Physics and Key Laboratory of Micro- and Nano-Photonic Structure (MOE), Fudan University, 200433, Shanghai, China
| | - Chuanshan Tian
- Department of Physics, State Key Laboratory of Surface Physics and Key Laboratory of Micro- and Nano-Photonic Structure (MOE), Fudan University, 200433, Shanghai, China.,Collaborative Innovation Center of Advanced Microstructures, 210093, Nanjing, China
| | - Lin He
- The Center for Advanced Quantum Studies, Department of Physics, Beijing Normal University, 100875, Beijing, China.
| | - Zengfeng Di
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 200050, Shanghai, China.
| | - Xi Wang
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 200050, Shanghai, China
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Koczorowski W, Grzela T, Radny MW, Schofield SR, Capellini G, Czajka R, Schroeder T, Curson NJ. Ba termination of Ge(001) studied with STM. NANOTECHNOLOGY 2015; 26:155701. [PMID: 25797886 DOI: 10.1088/0957-4484/26/15/155701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We use controlled annealing to tune the interfacial properties of a sub-monolayer and monolayer coverages of Ba atoms deposited on Ge(001), enabling the generation of either of two fundamentally distinct interfacial phases, as revealed by scanning tunneling microscopy. Firstly we identify the two key structural phases associated with this adsorption system, namely on-top adsorption and surface alloy formation, by performing a deposition and annealing experiment at a coverage low enough (∼0.15 ML) that isolated Ba-related features can be individually resolved. Subsequently we investigate the monolayer coverage case, of interest for passivation schemes of future Ge based devices, for which we find that the thermal evaporation of Ba onto a Ge(001) surface at room temperature results in on-top adsorption. This separation (lack of intermixing) between Ba and Ge layers is retained through successive annealing steps to temperatures of 470, 570, 670 and 770 K although a gradual ordering of the Ba layer is observed at 570 K and above, accompanied by a decrease in Ba layer density. Annealing above 770 K produces the 2D surface alloy phase accompanied by strain relief through monolayer height trench formation. An annealing temperature of 1070 K sees a further change in surface morphology but retention of the 2D surface alloy characteristic. These results are discussed in view of their possible implications for future semiconductor integrated circuit technology.
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Affiliation(s)
- W Koczorowski
- London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London, UK. Institute of Physics, Poznan University of Technology, ul. Piotrowo 3, 60-965 Poznan, Poland
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Scappucci G, Capellini G, Klesse WM, Simmons MY. New avenues to an old material: controlled nanoscale doping of germanium. NANOSCALE 2013; 5:2600-2615. [PMID: 23455600 DOI: 10.1039/c3nr34258a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We review our recent research into n-type doping of Ge for nanoelectronics and integrated photonics. We demonstrate a doping method in ultra-high vacuum to achieve high electron concentrations in Ge while maintaining atomic-level control of the doping process. We integrated this doping technique with ultra-high vacuum scanning tunneling microscope lithography and femtosecond laser ablation micron-scale lithography, and demonstrated basic components of donor-based nanoelectronic circuitry such as wires and tunnel gaps. By repetition of controlled doping cycles we have shown that stacking of multiple Ge:P two-dimensional electron gases results in high electron densities in Ge (>10(20) cm(-3)). Because of the strong vertical electron confinement, closely stacked 2D layers - although interacting - maintain their individuality in terms of electron transport. These results bode well towards the realization of nanoscale 3D epitaxial circuits in Ge comprising stacked 2DEGs and/or atomic-scale Ge:P devices with confinement in more dimensions.
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Affiliation(s)
- Giordano Scappucci
- School of Physics, University of New South Wales, Sydney, NSW 2052, Australia.
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Scappucci G, Capellini G, Johnston B, Klesse WM, Miwa JA, Simmons MY. A complete fabrication route for atomic-scale, donor-based devices in single-crystal germanium. NANO LETTERS 2011; 11:2272-2279. [PMID: 21553900 DOI: 10.1021/nl200449v] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Despite the rapidly growing interest in Ge for ultrascaled classical transistors and innovative quantum devices, the field of Ge nanoelectronics is still in its infancy. One major hurdle has been electron confinement since fast dopant diffusion occurs when traditional Si CMOS fabrication processes are applied to Ge. We demonstrate a complete fabrication route for atomic-scale, donor-based devices in single-crystal Ge using a combination of scanning tunneling microscope lithography and high-quality crystal growth. The cornerstone of this fabrication process is an innovative lithographic procedure based on direct laser patterning of the semiconductor surface, allowing the gap between atomic-scale STM-patterned structures and the outside world to be bridged. Using this fabrication process, we show electron confinement in a 5 nm wide phosphorus-doped nanowire in single-crystal Ge. At cryogenic temperatures, Ohmic behavior is observed and a low planar resistivity of 8.3 kΩ/□ is measured.
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Affiliation(s)
- G Scappucci
- School of Physics, University of New South Wales, Sydney, NSW 2052, Australia.
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Klesse WM, Scappucci G, Capellini G, Simmons MY. Preparation of the Ge(001) surface towards fabrication of atomic-scale germanium devices. NANOTECHNOLOGY 2011; 22:145604. [PMID: 21368353 DOI: 10.1088/0957-4484/22/14/145604] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We demonstrate the preparation of a clean Ge(001) surface with minimal roughness (RMS ~0.6 Å), low defect densities (~0.2% ML) and wide mono-atomic terraces (~80-100 nm). We use an ex situ wet chemical process combined with an in situ anneal treatment followed by a homoepitaxial buffer layer grown by molecular beam epitaxy and a subsequent final thermal anneal. Using scanning tunneling microscopy, we investigate the effect on the surface morphology of using different chemical reagents, concentrations as well as substrate temperature during growth. Such a high quality Ge(001) surface enables the formation of defect-free H-terminated Ge surfaces for subsequent patterning of atomic-scale devices by scanning tunneling lithography. We have achieved atomic-scale dangling bond wire structures 1.6 nm wide and 40 nm long as well as large, micron-size patterns with clear contrast of lithography in STM images.
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Affiliation(s)
- W M Klesse
- School of Physics, University of New South Wales, Sydney, NSW 2052, Australia
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