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Tai YC, Tzeng WY, Lin JD, Kuo YH, Chen FXR, Tu RJ, Huang MY, Pai SS, Chang NW, Tseng SY, Chen C, Lin CL, Yabushita A, Cheng SJ, Luo CW. Directly Unveiling the Energy Transfer Dynamics between Alq 3 Molecules and Si by Ultrafast Optical Pump-Probe Spectroscopy. NANO LETTERS 2023; 23:10490-10497. [PMID: 37909686 DOI: 10.1021/acs.nanolett.3c03251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2023]
Abstract
The energy transfer (ET) between organic molecules and semiconductors is a crucial mechanism for enhancing the performance of semiconductor-based optoelectronic devices, but it remains undiscovered. Here, ultrafast optical pump-probe spectroscopy was utilized to directly reveal the ET between organic Alq3 molecules and Si semiconductors. Ultrathin SiO2 dielectric layers with a thickness of 3.2-10.8 nm were inserted between Alq3 and Si to prevent charge transfer. By means of the ET from Alq3 to Si, the SiO2 thickness-dependent relaxation dynamics of photoexcited carriers in Si have been unambiguously observed on the transient reflectivity change (ΔR/R) spectra, especially for the relaxation process on a time scale of 200-350 ps. In addition, these findings also agree with the results of our calculation in a model of long-range dipole-dipole interactions, which provides critical information for developing future optoelectronic devices.
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Affiliation(s)
- Yu-Chan Tai
- Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
| | - Wen-Yen Tzeng
- Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
- Department of Electronic Engineering, National Formosa University, Yunlin 632, Taiwan
| | - Jhen-Dong Lin
- Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
| | - Yi-Hou Kuo
- Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
| | - Fu-Xiang Rikudo Chen
- Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
| | - Ruei-Jhe Tu
- Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
| | - Ming-Yang Huang
- Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
| | - Shyh-Shii Pai
- FAB 12B, Taiwan Semiconductor Manufacturing Company, Ltd., Hsinchu 300, Taiwan
| | - Nick Weihan Chang
- FAB 12B, Taiwan Semiconductor Manufacturing Company, Ltd., Hsinchu 300, Taiwan
| | - Sheng-Yang Tseng
- FAB 12B, Taiwan Semiconductor Manufacturing Company, Ltd., Hsinchu 300, Taiwan
| | - Chi Chen
- Research Center for Applied Sciences, Academia Sinica, Taipei 115, Taiwan
| | - Chun-Liang Lin
- Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
| | - Atsushi Yabushita
- Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
| | - Shun-Jen Cheng
- Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
| | - Chih-Wei Luo
- Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
- Institute of Physics and Center for Emergent Functional Matter Science, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
- National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan
- Taiwan Consortium of Emergent Crystalline Materials (TCECM), National Science and Technology Council, Taipei 115, Taiwan
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
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2
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Zhou W, Zhang Z, Zhang Q, Qi D, Xu T, Dai S, Shen X. Transient Study of Femtosecond Laser-Induced Ge 2Sb 2Te 5 Phase Change Film Morphology. MICROMACHINES 2021; 12:mi12060616. [PMID: 34071820 PMCID: PMC8229194 DOI: 10.3390/mi12060616] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 04/05/2021] [Accepted: 04/11/2021] [Indexed: 11/16/2022]
Abstract
Femtosecond laser-induced crystallization and ablation of Ge2Sb2Te5 (GST) phase change film is investigated by reflectivity pump-probing technology. Below the ablation threshold, the face-centered cubic structure (FCC) state in the central area can be formed, and cylindrical rims are formed in the peripheral dewetting zone due to the solidification of transported matter. The time of surface temperature dropping to the crystallization point needs about 30 ps for 5.86 mJ/cm2 and 82 ps for 7.04 mJ/cm2, respectively. At higher laser fluence, crystallization GST island structures appear in the central ablation region due to the extremely short heating time (100 ps). Furthermore, crystallization rate is faster than the ablation rate of the GST film, which is caused by different reflectivity.
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Affiliation(s)
- Wenju Zhou
- Laboratory of Infrared Materials and Devices, Ningbo University, Ningbo 315211, China; (W.Z.); (Q.Z.); (S.D.); (X.S.)
- Center for Advanced Laser Manufacturing (CALM), Shandong University of Technology, Zibo 255000, China
| | - Zifeng Zhang
- College of Mechanical and Electronic Engineering, Chaohu University, Hefei 230000, China;
| | - Qingwei Zhang
- Laboratory of Infrared Materials and Devices, Ningbo University, Ningbo 315211, China; (W.Z.); (Q.Z.); (S.D.); (X.S.)
| | - Dongfeng Qi
- Center for Advanced Laser Manufacturing (CALM), Shandong University of Technology, Zibo 255000, China
- Correspondence: (D.Q.); (T.X.)
| | - Tianxiang Xu
- Laboratory of Infrared Materials and Devices, Ningbo University, Ningbo 315211, China; (W.Z.); (Q.Z.); (S.D.); (X.S.)
- Correspondence: (D.Q.); (T.X.)
| | - Shixun Dai
- Laboratory of Infrared Materials and Devices, Ningbo University, Ningbo 315211, China; (W.Z.); (Q.Z.); (S.D.); (X.S.)
| | - Xiang Shen
- Laboratory of Infrared Materials and Devices, Ningbo University, Ningbo 315211, China; (W.Z.); (Q.Z.); (S.D.); (X.S.)
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3
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Nakamura A, Shimojima T, Ishizaka K. Finite-element simulation of photoinduced strain dynamics in silicon thin plates. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2021; 8:024103. [PMID: 33907699 PMCID: PMC8051961 DOI: 10.1063/4.0000059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 03/29/2021] [Indexed: 11/14/2022]
Abstract
In this paper, we investigate the femtosecond-optical-pulse-induced strain dynamics in relatively thin (100 nm) and thick (10 000 nm) silicon plates based on finite-element simulations. In the thin sample, almost spatially homogeneous excitation by the optical pulse predominantly generates a standing wave of the lowest-order acoustic resonance mode along the out-of-plane direction. At the same time, laterally propagating plate waves are emitted at the sample edge through the open edge deformation. Fourier transformation analysis reveals that the plate waves in the thin sample are mainly composed of two symmetric Lamb waves, reflecting the spatially uniform photoexcitation. In the thick sample, on the other hand, only the near surface region is photo-excited and thus a strain pulse that propagates along the out-of-plane direction is generated, accompanying the laterally propagating pulse-like strain dynamics through the edge deformation. These lateral strain pulses consist of multiple Lamb waves, including asymmetric and higher-order symmetric modes. Our simulations quantitatively demonstrate the out-of-plane and in-plane photoinduced strain dynamics in realistic silicon plates, ranging from the plate wave form to pulse trains, depending on material parameters such as sample thickness, optical penetration depth, and sound velocity.
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Affiliation(s)
- A. Nakamura
- RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan
| | - T. Shimojima
- RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan
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4
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Li M, Fu J, Xu Q, Sum TC. Slow Hot-Carrier Cooling in Halide Perovskites: Prospects for Hot-Carrier Solar Cells. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1802486. [PMID: 30600555 DOI: 10.1002/adma.201802486] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 09/24/2018] [Indexed: 05/25/2023]
Abstract
Rapid hot-carrier cooling is a major loss channel in solar cells. Thermodynamic calculations reveal a 66% solar conversion efficiency for single junction cells (under 1 sun illumination) if these hot carriers are harvested before cooling to the lattice temperature. A reduced hot-carrier cooling rate for efficient extraction is a key enabler to this disruptive technology. Recently, halide perovskites emerge as promising candidates with favorable hot-carrier properties: slow hot-carrier cooling lifetimes several orders of magnitude longer than conventional solar cell absorbers, long-range hot-carrier transport (up to ≈600 nm), and highly efficient hot-carrier extraction (up to ≈83%). This review presents the developmental milestones, distills the complex photophysical findings, and highlights the challenges and opportunities in this emerging field. A developmental toolbox for engineering the slow hot-carrier cooling properties in halide perovskites and prospects for perovskite hot-carrier solar cells are also discussed.
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Affiliation(s)
- Mingjie Li
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore
| | - Jianhui Fu
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore
| | - Qiang Xu
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore
| | - Tze Chien Sum
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore
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5
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Boyd KMW, Kleiman RN. Single-beam lifetime measurements via self-induced optical absorption. OPTICS EXPRESS 2019; 27:4445-4461. [PMID: 30876063 DOI: 10.1364/oe.27.004445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 01/17/2019] [Indexed: 06/09/2023]
Abstract
We present self-induced absorption, a pump/probe-like modulation technique that uses a single monochromatic laser acting simultaneously as both a pump and a probe. The technique is applicable to any system where the phenomenon that us being excited simultaneously induces additional absorption in the beam through a secondary process, leading to a non-linear power component in the beam transmission. The technique is demonstrated on a silicon wafer, where the non-linear transmission is due to free-carrier absorption, and provides information about the recombination lifetime of the semiconductor. Reducing a two-beam technique to a single laser beam simplifies the alignment challenges of traditional dual-beam modulated pump/probe measurements, which require overlap of separate pump and probe lasers on the sample under study.
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6
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Zhong C, Sangwan VK, Kang J, Luxa J, Sofer Z, Hersam MC, Weiss EA. Hot Carrier and Surface Recombination Dynamics in Layered InSe Crystals. J Phys Chem Lett 2019; 10:493-499. [PMID: 30642181 DOI: 10.1021/acs.jpclett.8b03543] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Layered indium selenide (InSe) is a van der Waals solid that has emerged as a promising material for high-performance ultrathin solar cells. The optoelectronic parameters that are critical to photoconversion efficiencies, such as hot carrier lifetime and surface recombination velocity, are however largely unexplored in InSe. Here, these key photophysical properties of layered InSe are measured with femtosecond transient reflection spectroscopy. The hot carrier cooling process is found to occur through phonon scattering. The surface recombination velocity and ambipolar diffusion coefficient are extracted from fits to the pump energy-dependent transient reflection kinetics using a free carrier diffusion model. The extracted surface recombination velocity is approximately an order of magnitude larger than that for methylammonium lead-iodide perovskites, suggesting that surface recombination is a principal source of photocarrier loss in InSe. The extracted ambipolar diffusion coefficient is consistent with previously reported values of InSe carrier mobility.
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Affiliation(s)
- Chengmei Zhong
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
| | - Vinod K Sangwan
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
| | - Joohoon Kang
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
| | - Jan Luxa
- Department of Inorganic Chemistry , University of Chemistry and Technology Prague , Technicka 5 , 166 28 Prague 6, Czech Republic
| | - Zdeněk Sofer
- Department of Inorganic Chemistry , University of Chemistry and Technology Prague , Technicka 5 , 166 28 Prague 6, Czech Republic
| | - Mark C Hersam
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
| | - Emily A Weiss
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
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7
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Glassner S, Keshmiri H, Hill DJ, Cahoon JF, Fernandez B, den Hertog MI, Lugstein A. Tuning Electroluminescence from a Plasmonic Cavity-Coupled Silicon Light Source. NANO LETTERS 2018; 18:7230-7237. [PMID: 30335400 DOI: 10.1021/acs.nanolett.8b03391] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The combination of Moore's law and Dennard's scaling rules have constituted the fundamental guidelines for the silicon-based semiconductor industry for decades. Furthermore, the enormous growth of global data volume has pushed the demand for complex and densely packed devices. In recent years, it has become clear that wired interconnects impose increasingly severe speed and power limitations onto integrated circuits as scaling slows toward a halt. To overcome these limitations, there is a clear need for optical data processing. Despite significant progress in the development of silicon photonics, light sources remain challenging owing to the indirect bandgap of group IV materials. It is therefore highly desirable to develop new concepts for a silicon light source that meets efficiency and footprint requirements similar to their electronic counterparts. Here, we demonstrate an electrically driven and tunable silicon light source by matching the resonant modes of a silver nanocavity with the hot luminescence spectrum of an avalanching p-n junction. The cavity significantly enhances phonon-assisted recombination of hot carriers by tailoring the local density of states at the size-tunable resonance. Such tunable nanoscale emitter may be of great interest for short-reach communications, microdisplays or lab-on-chip applications.
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Affiliation(s)
- S Glassner
- Institute of Solid State Electronics , TU Wien , Gußhausstraße 25-25a , 1040 Vienna , Austria
| | - H Keshmiri
- Institute of Solid State Electronics , TU Wien , Gußhausstraße 25-25a , 1040 Vienna , Austria
- Vienna Biocenter Core Facilities GmbH , Dr. Bohr-Gasse 3 , 1030 Vienna , Austria
| | - D J Hill
- Department of Chemistry , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599-3290 , United States
| | - J F Cahoon
- Department of Chemistry , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599-3290 , United States
| | - B Fernandez
- Institut NEEL CNRS/UGA UPR2940 , 25 avenue des Martyrs , 38042 Grenoble , France
| | - M I den Hertog
- Institut NEEL CNRS/UGA UPR2940 , 25 avenue des Martyrs , 38042 Grenoble , France
| | - A Lugstein
- Institute of Solid State Electronics , TU Wien , Gußhausstraße 25-25a , 1040 Vienna , Austria
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8
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Cushing SK, Zürch M, Kraus PM, Carneiro LM, Lee A, Chang HT, Kaplan CJ, Leone SR. Hot phonon and carrier relaxation in Si(100) determined by transient extreme ultraviolet spectroscopy. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2018; 5:054302. [PMID: 30246050 PMCID: PMC6133686 DOI: 10.1063/1.5038015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 08/22/2018] [Indexed: 05/16/2023]
Abstract
The thermalization of hot carriers and phonons gives direct insight into the scattering processes that mediate electrical and thermal transport. Obtaining the scattering rates for both hot carriers and phonons currently requires multiple measurements with incommensurate timescales. Here, transient extreme-ultraviolet (XUV) spectroscopy on the silicon 2p core level at 100 eV is used to measure hot carrier and phonon thermalization in Si(100) from tens of femtoseconds to 200 ps, following photoexcitation of the indirect transition to the Δ valley at 800 nm. The ground state XUV spectrum is first theoretically predicted using a combination of a single plasmon pole model and the Bethe-Salpeter equation with density functional theory. The excited state spectrum is predicted by incorporating the electronic effects of photo-induced state-filling, broadening, and band-gap renormalization into the ground state XUV spectrum. A time-dependent lattice deformation and expansion is also required to describe the excited state spectrum. The kinetics of these structural components match the kinetics of phonons excited from the electron-phonon and phonon-phonon scattering processes following photoexcitation. Separating the contributions of electronic and structural effects on the transient XUV spectra allows the carrier population, the population of phonons involved in inter- and intra-valley electron-phonon scattering, and the population of phonons involved in phonon-phonon scattering to be quantified as a function of delay time.
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Affiliation(s)
| | - Michael Zürch
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Peter M Kraus
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | | | - Angela Lee
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Hung-Tzu Chang
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Christopher J Kaplan
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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9
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Li L, Kanai Y. Dependence of hot electron transfer on surface coverage and adsorbate species at semiconductor–molecule interfaces. Phys Chem Chem Phys 2018; 20:12986-12991. [DOI: 10.1039/c7cp07247c] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Developing a molecular-level understanding of how a hot electron transfer process can be enhanced at semiconductor–molecule interfaces is central to advancing various future technologies.
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Affiliation(s)
- Lesheng Li
- Department of Chemistry
- University of North Carolina at Chapel Hill
- Chapel Hill
- North Carolina 27599
- USA
| | - Yosuke Kanai
- Department of Chemistry
- University of North Carolina at Chapel Hill
- Chapel Hill
- North Carolina 27599
- USA
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10
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Mu Z, Yu H, Zhang M, Wu A, Qi G, Chu PK, An Z, Di Z, Wang X. Multiband Hot Photoluminescence from Nanocavity-Embedded Silicon Nanowire Arrays with Tunable Wavelength. NANO LETTERS 2017; 17:1552-1558. [PMID: 28135102 DOI: 10.1021/acs.nanolett.6b04675] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Besides the well-known quantum confinement effect, hot luminescence from indirect bandgap Si provides a new and promising approach to realize monolithically integrated silicon optoelectronics due to phonon-assisted light emission. In this work, multiband hot photoluminescence is generated from Si nanowire arrays by introducing trapezoid-shaped nanocavities that support hybrid photonic-plasmonic modes. By continuously adjusting the geometric parameters of the Si nanowires with trapezoidal nanocavities, the multiband hot photoluminescence can be tuned in the range from visible to near-infrared independent of the excitation laser wavelength. The highly tunable wavelength bands and concomitant compatibility with Si-integrated electronics enable tailoring of silicon-based light sources suitable for next-generation optoelectronics devices.
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Affiliation(s)
- Zhiqiang Mu
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences , Shanghai 200050, People's Republic of China
| | | | - Miao Zhang
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences , Shanghai 200050, People's Republic of China
| | - Aimin Wu
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences , Shanghai 200050, People's Republic of China
| | - Gongmin Qi
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences , Shanghai 200050, People's Republic of China
| | - Paul K Chu
- Department of Physics and Materials Science, City University of Hong Kong , Tat Chee Avenue, Kowloon, Hong Kong, People's Republic of China
| | | | - Zengfeng Di
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences , Shanghai 200050, People's Republic of China
| | - Xi Wang
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences , Shanghai 200050, People's Republic of China
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11
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Rodriguez-Nieva JF, Dresselhaus MS, Song JCW. Enhanced Thermionic-Dominated Photoresponse in Graphene Schottky Junctions. NANO LETTERS 2016; 16:6036-6041. [PMID: 27598943 DOI: 10.1021/acs.nanolett.6b01965] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Vertical heterostructures of van der Waals materials enable new pathways to tune charge and energy transport characteristics in nanoscale systems. We propose that graphene Schottky junctions can host a special kind of photoresponse that is characterized by strongly coupled heat and charge flows that run vertically out of the graphene plane. This regime can be accessed when vertical energy transport mediated by thermionic emission of hot carriers overwhelms electron-lattice cooling as well as lateral diffusive energy transport. As such, the power pumped into the system is efficiently extracted across the entire graphene active area via thermionic emission of hot carriers into a semiconductor material. Experimental signatures of this regime include a large and tunable internal responsivity [Formula: see text] with a nonmonotonic temperature dependence. In particular, [Formula: see text] peaks at electronic temperatures on the order of the Schottky barrier potential ϕ and has a large upper limit [Formula: see text] (e/ϕ = 10 A/W when ϕ = 100 meV). Our proposal opens up new approaches for engineering the photoresponse in optically active graphene heterostructures.
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Affiliation(s)
| | | | - Justin C W Song
- Walter Burke Institute for Theoretical Physics and Institute of Quantum Information and Matter, California Institute of Technology , Pasadena, California 91125, United States
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12
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Luo K, Chen X, Peng Y, Zhu Y. Effects of femtosecond laser pulse width on the formation of microstructured silicon. APPLIED OPTICS 2016; 55:6079-6082. [PMID: 27505391 DOI: 10.1364/ao.55.006079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We experimentally investigated the properties of surface microstructured silicon fabricated by 15 and 130 fs laser pulses. By changing parameters of femtosecond laser pulses, including laser flux, actual pulse acting time, and laser peak intensity, we found that the average height of spikes on the surface of microstructured silicon are only determined by the laser peak intensity. These results are important for the preparation and structure control of microstructured silicon.
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13
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Kong J, Rose AH, Yang C, Wu X, Merlo JM, Burns MJ, Naughton MJ, Kempa K. Hot electron plasmon-protected solar cell. OPTICS EXPRESS 2015; 23:A1087-A1095. [PMID: 26406739 DOI: 10.1364/oe.23.0a1087] [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
A solar cell based on a hot electron plasmon protection effect is proposed and made plausible by simulations, non-local modeling of the response, and quantum mechanical calculations. In this cell, a thin-film, plasmonic metamaterial structure acts as both an efficient photon absorber in the visible frequency range and a plasmonic resonator in the IR range, the latter of which absorbs and protects against phonon emission the free energy of the hot electrons in an adjacent semiconductor junction. We show that in this structure, electron-plasmon scattering is much more efficient than electron-phonon scattering in cooling-off hot electrons, and the plasmon-stored energy is recoverable as an additional cell voltage. The proposed structure could become a prototype of a new generation of high efficiency solar cells.
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14
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Premnath P, Venkatakrishnan K, Tan B. Programming cancer through phase-functionalized silicon based biomaterials. Sci Rep 2015; 5:10826. [PMID: 26043430 PMCID: PMC4455305 DOI: 10.1038/srep10826] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 04/17/2015] [Indexed: 11/09/2022] Open
Abstract
Applications of biomaterials in cancer therapy has been limited to drug delivery systems and markers in radiation therapy. In this article, we introduce the concept of phase-functionalization of silicon to preferentially select cancer cell populations for survival in a catalyst and additive free approach. Silicon is phase-functionalized by the interaction of ultrafast laser pulses, resulting in the formation of rare phases of SiO2 in conjunction with differing silicon crystal lattices. The degree of phase-functionalization is programmed to dictate the degree of repulsion of cancer cells. Unstable phases of silicon oxides are synthesized during phase-functionalization and remain stable at ambient conditions. This change in phase of silicon as well as formation of oxides contributes to changes in surface chemistry as well as surface energy. These material properties elicit in precise control of migration, cytoskeleton shape, direction and population. To the best of our knowledge, phase-functionalized silicon without any changes in topology or additive layers and its applications in cancer therapy has not been reported before. This unique programmable phase-functionalized silicon has the potential to change current trends in cancer research and generate focus on biomaterials as cancer repelling or potentially cancer killing surfaces.
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Affiliation(s)
- Priyatha Premnath
- Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto M5B2K3
| | - Krishnan Venkatakrishnan
- Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto M5B2K3
| | - Bo Tan
- Department of Aerospace Engineering, Ryerson University, 350 Victoria Street, Toronto M5B2K3
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15
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Aspetti CO, Agarwal R. Tailoring the Spectroscopic Properties of Semiconductor Nanowires via Surface-Plasmon-Based Optical Engineering. J Phys Chem Lett 2014; 5:3768-3780. [PMID: 25396030 PMCID: PMC4226303 DOI: 10.1021/jz501823d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 10/10/2014] [Indexed: 05/28/2023]
Abstract
Semiconductor nanowires, due to their unique electronic, optical, and chemical properties, are firmly placed at the forefront of nanotechnology research. The rich physics of semiconductor nanowire optics arises due to the enhanced light-matter interactions at the nanoscale and coupling of optical modes to electronic resonances. Furthermore, confinement of light can be taken to new extremes via coupling to the surface plasmon modes of metal nanostructures integrated with nanowires, leading to interesting physical phenomena. This Perspective will examine how the optical properties of semiconductor nanowires can be altered via their integration with highly confined plasmonic nanocavities that have resulted in properties such as orders of magnitude faster and more efficient light emission and lasing. The use of plasmonic nanocavities for tailored optical absorption will also be discussed in order to understand and engineer fundamental optical properties of these hybrid systems along with their potential for novel applications, which may not be possible with purely dielectric cavities.
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16
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Aspetti C, Cho CH, Agarwal R, Agarwal R. Studies of hot photoluminescence in plasmonically coupled silicon via variable energy excitation and temperature-dependent spectroscopy. NANO LETTERS 2014; 14:5413-22. [PMID: 25120156 PMCID: PMC4160267 DOI: 10.1021/nl502606q] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Revised: 07/27/2014] [Indexed: 05/26/2023]
Abstract
By integrating silicon nanowires (∼150 nm diameter, 20 μm length) with an Ω-shaped plasmonic nanocavity, we are able to generate broadband visible luminescence, which is induced by high order hybrid nanocavity-surface plasmon modes. The nature of this super bandgap emission is explored via photoluminescence spectroscopy studies performed with variable laser excitation energies (1.959 to 2.708 eV) and finite difference time domain simulations. Furthermore, temperature-dependent photoluminescence spectroscopy shows that the observed emission corresponds to radiative recombination of unthermalized (hot) carriers as opposed to a resonant Raman process.
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Affiliation(s)
- Carlos
O. Aspetti
- Department
of Materials Science and Engineering, University
of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Chang-Hee Cho
- Department
of Emerging Materials Science, Daegu Gyeongbuk
Institute of Science and Technology (DGIST), Daegu 711-873, Korea
| | - Rahul Agarwal
- Department
of Materials Science and Engineering, University
of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Ritesh Agarwal
- Department
of Materials Science and Engineering, University
of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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Piccione B, Aspetti CO, Cho CH, Agarwal R. Tailoring light-matter coupling in semiconductor and hybrid-plasmonic nanowires. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2014; 77:086401. [PMID: 25093385 PMCID: PMC4859436 DOI: 10.1088/0034-4885/77/8/086401] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Understanding interactions between light and matter is central to many fields, providing invaluable insights into the nature of matter. In its own right, a greater understanding of light-matter coupling has allowed for the creation of tailored applications, resulting in a variety of devices such as lasers, switches, sensors, modulators, and detectors. Reduction of optical mode volume is crucial to enhancing light-matter coupling strength, and among solid-state systems, self-assembled semiconductor and hybrid-plasmonic nanowires are amenable to creation of highly-confined optical modes. Following development of unique spectroscopic techniques designed for the nanowire morphology, carefully engineered semiconductor nanowire cavities have recently been tailored to enhance light-matter coupling strength in a manner previously seen in optical microcavities. Much smaller mode volumes in tailored hybrid-plasmonic nanowires have recently allowed for similar breakthroughs, resulting in sub-picosecond excited-state lifetimes and exceptionally high radiative rate enhancement. Here, we review literature on light-matter interactions in semiconductor and hybrid-plasmonic monolithic nanowire optical cavities to highlight recent progress made in tailoring light-matter coupling strengths. Beginning with a discussion of relevant concepts from optical physics, we will discuss how our knowledge of light-matter coupling has evolved with our ability to produce ever-shrinking optical mode volumes, shifting focus from bulk materials to optical microcavities, before moving on to recent results obtained from semiconducting nanowires.
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Affiliation(s)
- Brian Piccione
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Carlos O. Aspetti
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Chang-Hee Cho
- Department of Emerging Materials Science, Daegu Gyeongbuk Institute of Science & Technology, Dalseong-Gun, Daegu 711-873, Republic of Korea
| | - Ritesh Agarwal
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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Sieradzki A, Basta M, Scharoch P, Bigot JY. Ultrafast Optical Properties of Dense Electron Gas in Silicon Nanostructures. PLASMONICS (NORWELL, MASS.) 2013; 9:545-551. [PMID: 24834018 PMCID: PMC4018487 DOI: 10.1007/s11468-013-9658-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Accepted: 12/02/2013] [Indexed: 06/03/2023]
Abstract
We investigate the ultrafast dynamics of carriers in a silicon nanostructure by performing spectrally resolved femtosecond spectroscopy measurements with a supercontinuum probe. The nanostructure consists of a 158-nm-thick crystalline Si layer on top of which a SiO2 passivation layer leads to a very high quality of the Si surface. In addition, a dielectric function approach, including contributions from a Drude part and interband transitions, combined with the Transition Matrix Approximation is used to model the photogenerated carrier dynamics. The spectrotemporal reflectivity reveals two mechanisms. First, an electron-hole plasma is created by the pump pulse and lasts for a few picoseconds. Importantly, its spectral signature is either a positive or a negative change of reflectivity, depending on the probe wavelength. This is complementary to the already reported results obtained with degenerate frequency measurements. The second mechanism is a thermal diffusion of carriers which occurs during several hundreds of picoseconds. The overall dynamics at short and long delays in the whole visible spectrum is well explained with our model which shows that the main contribution to the reflectivity dynamics is due to the Drude dielectric function. The observation of this predominance of free carriers requires both a long lived high density of carriers as well as a little influence of surface scattering as provided by our thin crystalline Si layer with passivated Si/SiO2 interface.
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Affiliation(s)
- A. Sieradzki
- Institute of Physics, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wroclaw, Poland
- Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, CNRS, Université de Strasbourg, BP 43, 23 rue du Loess, 67034 Strasbourg Cedex 02, France
| | - M. Basta
- Department of Nanotechnology, Wroclaw Research Centre EiT+, ul Stabłowicka 147, 54-066 Wrocław, Poland
| | - P. Scharoch
- Institute of Physics, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wroclaw, Poland
| | - J.-Y. Bigot
- Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, CNRS, Université de Strasbourg, BP 43, 23 rue du Loess, 67034 Strasbourg Cedex 02, France
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Sieradzki A, Kuznicki ZT. Effects of Carrier Confinement and Intervalley Scattering on Photoexcited Electron Plasma in Silicon. PLASMONICS (NORWELL, MASS.) 2013; 8:1643-1646. [PMID: 24273470 PMCID: PMC3827834 DOI: 10.1007/s11468-013-9582-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Accepted: 05/22/2013] [Indexed: 06/02/2023]
Abstract
The ultrafast reflectivity of silicon, excited and probed with femtosecond laser pulses, is studied for different wavelengths and energy densities. The confinement of carriers in a thin surface layer delimited by a nanoscale Si-layered system buried in a Si heavily-doped wafer reduces the critical density of carriers necessary to create the electron plasma by a factor of ten. We performed two types of reflectivity measurements, using either a single beam or two beams. The plasma strongly depends on the photon energy density because of the intervalley scattering of the electrons revealed by two different mechanisms assisted by the electron-phonon interaction. One mechanism leads to a negative differential reflectivity that can be attributed to an induced absorption in X valleys. The other mechanism occurs, when the carrier population is thermalizing and gives rise to a positive differential reflectivity corresponding to Pauli-blocked intervalley gamma to X scattering. These results are important for improving the efficiency of Si light-to-electricity converters, in which there is a possibility of multiplying carriers by nanostructurization of Si.
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Affiliation(s)
- A. Sieradzki
- Institute of Physics, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
- Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, CNRS, Université de Strasbourg, BP 43, 23 rue du Loess, 67034 Strasbourg, France
| | - Z. T. Kuznicki
- Photonic Systems Laboratory, Pôle API Parc d’Innovation, Boulevard Sébastien Brant, BP 10413, 67400 Illkirch, France
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21
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Johnson JA, Maznev AA, Cuffe J, Eliason JK, Minnich AJ, Kehoe T, Torres CMS, Chen G, Nelson KA. Direct measurement of room-temperature nondiffusive thermal transport over micron distances in a silicon membrane. PHYSICAL REVIEW LETTERS 2013; 110:025901. [PMID: 23383915 DOI: 10.1103/physrevlett.110.025901] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2012] [Indexed: 05/16/2023]
Abstract
The "textbook" phonon mean free path of heat carrying phonons in silicon at room temperature is ∼40 nm. However, a large contribution to the thermal conductivity comes from low-frequency phonons with much longer mean free paths. We present a simple experiment demonstrating that room-temperature thermal transport in Si significantly deviates from the diffusion model already at micron distances. Absorption of crossed laser pulses in a freestanding silicon membrane sets up a sinusoidal temperature profile that is monitored via diffraction of a probe laser beam. By changing the period of the thermal grating we vary the heat transport distance within the range ∼1-10 μm. At small distances, we observe a reduction in the effective thermal conductivity indicating a transition from the diffusive to the ballistic transport regime for the low-frequency part of the phonon spectrum.
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Affiliation(s)
- Jeremy A Johnson
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
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22
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Cho CH, Aspetti CO, Park J, Agarwal R. Silicon coupled with plasmon nanocavity generates bright visible hot-luminescence. NATURE PHOTONICS 2013; 7:285-289. [PMID: 23710256 PMCID: PMC3661302 DOI: 10.1038/nphoton.2013.25] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Due to limitations in device speed and performance of silicon-based electronics, silicon optoelectronics has been extensively studied to achieve ultrafast optical-data processing1-3. However, the biggest challenge has been to develop an efficient silicon-based light source since indirect band-gap of silicon gives rise to extremely low emission efficiency. Although light emission in quantum-confined silicon at sub-10 nm lengthscales has been demonstrated4-7, there are difficulties in integrating quantum structures with conventional electronics8,9. It is desirable to develop new concepts to obtain emission from silicon at lengthscales compatible with current electronic devices (20-100 nm), which therefore do not utilize quantum-confinement effects. Here, we demonstrate an entirely new method to achieve bright visible light emission in "bulk-sized" silicon coupled with plasmon nanocavities from non-thermalized carrier recombination. Highly enhanced emission quantum efficiency (>1%) in plasmonic silicon, along with its size compatibility with present silicon electronics, provides new avenues for developing monolithically integrated light-sources on conventional microchips.
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23
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Lin Z, Allen RE. Ultrafast equilibration of excited electrons in dynamical simulations. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:485503. [PMID: 21832522 DOI: 10.1088/0953-8984/21/48/485503] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In our density-functional-based simulations of materials responding to femtosecond-scale laser pulses, we have observed a potentially useful phenomenon: the excited electrons automatically equilibrate to a Fermi-Dirac distribution within ∼100 fs, solely because of their coupling to the nuclear motion, even though the resulting electronic temperature is one to two orders of magnitude higher than the kinetic temperature defined by the nuclear motion. Microscopic simulations like these can then provide the separate electronic and kinetic temperatures, chemical potentials, pressures, and nonhydrostatic stresses as input for studies on larger lengths and timescales.
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24
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Yurtsever A, Zewail AH. 4D Nanoscale Diffraction Observed by Convergent-Beam Ultrafast Electron Microscopy. Science 2009; 326:708-12. [DOI: 10.1126/science.1179314] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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25
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Ichibayashi T, Tanimura K. Ultrafast carrier relaxation in Si studied by time-resolved two-photon photoemission spectroscopy: intravalley scattering and energy relaxation of hot electrons. PHYSICAL REVIEW LETTERS 2009; 102:087403. [PMID: 19257784 DOI: 10.1103/physrevlett.102.087403] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2008] [Indexed: 05/27/2023]
Abstract
The dynamical relaxations of photogenerated hot carriers in the X valley of Si have been studied using time-resolved two-photon photoemission spectroscopy. Intravalley scattering is completed within 100 fs to form a quasiequilibrated electron distribution near the conduction-band minimum, while maintaining about half the excess energy given to hot electrons. The energy relaxation follows the scattering with a 240-fs time constant that is independent of the excess energy.
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Affiliation(s)
- T Ichibayashi
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
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26
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Gurevich EL, Hergenröder R. Femtosecond laser-induced breakdown spectroscopy: physics, applications, and perspectives. APPLIED SPECTROSCOPY 2007; 61:233A-242A. [PMID: 17958949 DOI: 10.1366/000370207782217824] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Affiliation(s)
- E L Gurevich
- ISAS-Institute for Analytical Sciences, Bunsen-Kirchhoff-Strasse, 11, 44139, Dortmund, Germany
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27
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Maksymovych P, Dougherty DB, Zhu XY, Yates JT. Nonlocal dissociative chemistry of adsorbed molecules induced by localized electron injection into metal surfaces. PHYSICAL REVIEW LETTERS 2007; 99:016101. [PMID: 17678164 DOI: 10.1103/physrevlett.99.016101] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2007] [Indexed: 05/16/2023]
Abstract
We present a novel approach to surface chemistry studies using scanning tunneling microscopy (STM), where dissociation of molecules adsorbed on metal surfaces is induced nonlocally in a 10-100 nm radius around the STM tip by hot electrons that originate from the STM tip and transport on the surface. Nonlocal molecular excitation eliminates the influence of the STM tip on the outcome of the electron-induced chemical reaction. The spatial attenuation of the nonlocal reaction is used as a direct measure of hot-electron transport on the surface.
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Affiliation(s)
- Peter Maksymovych
- Surface Science Center, Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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28
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Harb M, Ernstorfer R, Dartigalongue T, Hebeisen CT, Jordan RE, Miller RJD. Carrier Relaxation and Lattice Heating Dynamics in Silicon Revealed by Femtosecond Electron Diffraction. J Phys Chem B 2006; 110:25308-13. [PMID: 17165976 DOI: 10.1021/jp064649n] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report on the use of femtosecond electron diffraction to resolve the dynamics of electron-phonon relaxation in silicon. Nanofabricated free-standing membranes of polycrystalline silicon were excited below the damage threshold with 387 nm light at a fluence of 5.6 mJ/cm2 absorbed (corresponding to a carrier density of 2.2 x 10(21) cm(-3)). The diffraction pattern was captured over a range of delay times with a time resolution of 350 fs. All of the detected Bragg peaks exhibited intensity loss with a time constant of less than 2 ps. Beyond the initial decay, there was no further change in the diffracted intensity up to 700 ps. We find that the loss of intensity in the diffracted orders is accounted for by the Debye-Waller effect on a time scale indicative of a thermally driven process as opposed to an electronically driven one. Furthermore, the relaxation time constant is consistent with the excitation regime where the phonon emission rate is reduced due to carrier screening.
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Affiliation(s)
- Maher Harb
- Institute for Optical Sciences and Department of Physics, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
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29
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Hergenröder R, Miclea M, Hommes V. Controlling semiconductor nanoparticle size distributions with tailored ultrashort pulses. NANOTECHNOLOGY 2006; 17:4065-4071. [PMID: 21727539 DOI: 10.1088/0957-4484/17/16/012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The laser generation of size-controlled semiconductor nanoparticle formation under gas phase conditions is investigated. It is shown that the size distribution can be changed if picosecond pulse sequences of tailored ultra short laser pulses (<200 fs) are employed. By delivering the laser energy in small packages, a temporal energy flux control at the target surface is achieved, which results in the control of the thermodynamic pathway the material takes. The concept is tested with silicon and germanium, both materials with a predictable response to double pulse sequences, which allows deduction of the materials' response to complicated pulse sequences. An automatic, adaptive learning algorithm was employed to demonstrate a future strategy that enables the definition of more complex optimization targets such as particle size on materials less predictable than semiconductors.
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Affiliation(s)
- R Hergenröder
- ISAS-Institute for Analytical Sciences, Material Analysis, Bunsen-Kichhoff Strasse 11, 44139 Dortmund, Germany
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30
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Park JY, Somorjai GA. The Catalytic Nanodiode: Detecting Continous Electron Flow at Oxide-Metal Interfaces Generated by a Gas-Phase Exothermic Reaction. Chemphyschem 2006; 7:1409-13. [PMID: 16739158 DOI: 10.1002/cphc.200600056] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Continuous flow of ballistic charge carriers is generated by an exothermic chemical reaction and detected using the catalytic metal-semiconductor Schottky diode. We obtained a hot electron current for several hours using two types of catalytic nanodiodes, Pt/TiO2 or Pt/GaN, during carbon monoxide oxidation at pressures of 100 Torr of O2 and 40 Torr of CO at 413-573 K. This result reveals that the chemical energy of an exothermic catalytic reaction is directly converted into hot electrons flux in the catalytic nanodiode. By heating the nanodiodes in He, we could measure the thermoelectric current which is in the opposite direction to the flow of the hot electron current. The chemicurrent is well correlated with the turnover rate of CO oxidation, which is separately measured with gas chromatography. The influence of the flow of hot charge carriers on the chemistry at the oxide-metal interface, and the turnover rate in the chemical reaction are discussed.
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Affiliation(s)
- Jeong Young Park
- Materials Sciences and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Department of Chemistry, University of California, Berkeley, CA 94720, USA
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31
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Glover T, Ackerman G, Lee R, Padmore H, Young D. Metal–insulator transitions in an expanding metallic fluid: particle formation during femtosecond laser ablation. Chem Phys 2004. [DOI: 10.1016/j.chemphys.2003.11.042] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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32
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Weinelt M, Kutschera M, Fauster T, Rohlfing M. Dynamics of exciton formation at the Si(100) c(4 x 2) surface. PHYSICAL REVIEW LETTERS 2004; 92:126801. [PMID: 15089696 DOI: 10.1103/physrevlett.92.126801] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2003] [Indexed: 05/24/2023]
Abstract
Carrier recombination at the Si(100) c(4 x 2) surface and the underlying surface electronic structure is unraveled by a combination of two-photon photoemission and many-body perturbation theory: An electron excited to the silicon conduction band by a femtosecond infrared laser pulse scatters within 220 ps to the unoccupied surface band, needs 1.5 ps to jump to the band bottom via emission of optical phonons, and finally relaxes within 5 ps with an excited hole in the occupied surface band to form an exciton living for nanoseconds.
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Affiliation(s)
- Martin Weinelt
- Lehrstuhl für Festkörperphysik, Universität Erlangen-Nürnberg, Staudtstrasse 7, D-91058 Erlangen, Germany.
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33
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Voelkmann C, Reichelt M, Meier T, Koch SW, Höfer U. Five-wave-mixing spectroscopy of ultrafast electron dynamics at a si(001) surface. PHYSICAL REVIEW LETTERS 2004; 92:127405. [PMID: 15089707 DOI: 10.1103/physrevlett.92.127405] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2003] [Indexed: 05/24/2023]
Abstract
The optically induced electron dynamics at a Si(001) surface is studied using a five-wave-mixing setup which measures the diffracted second-harmonic intensity induced by three ultrashort (13 fs) laser pulses. Depending on the time ordering of the pulses, this technique is capable of monitoring the temporal evolution of photoexcited one- or two-photon coherences, or populations. For a particular pulse sequence, the experiments show a delayed rise and a decay of the diffracted signal intensity on time scales of 50 and 250 fs, respectively. This response can be described by optical Bloch equations by including rapid scattering of the photoexcited carriers in the D(down) band of Si(001).
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Affiliation(s)
- C Voelkmann
- Department of Physics and Material Sciences Center, Philipps University, Renthof 5, D-35032 Marburg, Germany
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Hase M, Kitajima M, Constantinescu AM, Petek H. The birth of a quasiparticle in silicon observed in time-frequency space. Nature 2003; 426:51-4. [PMID: 14603313 DOI: 10.1038/nature02044] [Citation(s) in RCA: 182] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2003] [Accepted: 09/08/2003] [Indexed: 11/09/2022]
Abstract
The concept of quasiparticles in solid-state physics is an extremely powerful tool for describing complex many-body phenomena in terms of single-particle excitations. Introducing a simple particle, such as an electron, hole or phonon, deforms a many-body system through its interactions with other particles. In this way, the added particle is 'dressed' or 'renormalized' by a self-energy cloud that describes the response of the many-body system, so forming a new entity--the quasiparticle. Using ultrafast laser techniques, it is possible to impulsively generate bare particles and observe their subsequent dressing by the many-body interactions (that is, quasiparticle formation) on the time and energy scales governed by the Heisenberg uncertainty principle. Here we describe the coherent response of silicon to excitation with a 10-femtosecond (10(-14) s) laser pulse. The optical pulse interacts with the sample by way of the complex second-order nonlinear susceptibility to generate a force on the lattice driving coherent phonon excitation. Transforming the transient reflectivity signal into frequency-time space reveals interference effects leading to the coherent phonon generation and subsequent dressing of the phonon by electron-hole pair excitations.
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Affiliation(s)
- Muneaki Hase
- Materials Engineering Laboratory, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
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35
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Glover TE, Ackerman GD, Belkacem A, Heimann PA, Hussain Z, Lee RW, Padmore HA, Ray C, Schoenlein RW, Steele WF, Young DA. Metal-insulator transitions in an expanding metallic fluid: particle formation kinetics. PHYSICAL REVIEW LETTERS 2003; 90:236102. [PMID: 12857274 DOI: 10.1103/physrevlett.90.236102] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2003] [Indexed: 05/24/2023]
Abstract
Core-level photoemission spectroscopy provides a local probe of expansion dynamics and associated transient chemical properties as a highly pressurized, metallic fluid expands into vacuum following impulsive heating of a semiconductor by an intense, ultrashort laser pulse. Transient photoemission peak shifts reveal that metal-insulator transitions occur rapidly following laser heating. These experiments probe constituents species and solidification kinetics occurring in the early moments of material ejection and provide insight into how particles arise in the current laser ablation regime.
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Affiliation(s)
- T E Glover
- Advanced Light Source Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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36
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Sjodin T, Li CM, Petek H, Dai HL. Ultrafast transient grating scattering studies of carrier dynamics at a silicon surface. Chem Phys 2000. [DOI: 10.1016/s0301-0104(99)00365-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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38
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Jeong S, Zacharias H, Bokor J. Ultrafast carrier dynamics on the Si(100)2 x 1 surface. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:R17300-R17303. [PMID: 9985942 DOI: 10.1103/physrevb.54.r17300] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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39
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Klushin DV, Gusev MY, Lysenko SA, Urazgil'din IF. Effect of the local electronic temperature on secondary-ion spectra. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:7062-7066. [PMID: 9984324 DOI: 10.1103/physrevb.54.7062] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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40
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Wolf M, Knoesel E, Hertel T. Ultrafast dynamics of electrons in image-potential states on clean and Xe-covered Cu(111). PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:R5295-R5298. [PMID: 9986592 DOI: 10.1103/physrevb.54.r5295] [Citation(s) in RCA: 119] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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41
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Femtosecond time-resolved photoemission study of hot electron relaxation at the GaAs(100) surface. Chem Phys 1996. [DOI: 10.1016/0301-0104(95)00328-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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42
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Hertel T, Knoesel E, Wolf M, Ertl G. Ultrafast electron dynamics at Cu(111): Response of an electron gas to optical excitation. PHYSICAL REVIEW LETTERS 1996; 76:535-538. [PMID: 10061481 DOI: 10.1103/physrevlett.76.535] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
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