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Title: Anisotropic picosecond photoconductivity caused by optical alignment of electron momenta in cubic semiconductors

Transient photoconductivity in cubic semiconductors InGaAs and InAs excited by a femtosecond laser pulse in the presence of a uniform dc electric field has been studied with the use of the Monte Carlo simulation by taking into account optical alignment of photoexcited electrons over their momenta. Simulations show that due to the optical alignment effect and energy dependence of the electron mobility, the transient photoconductivity in cubic semiconductors becomes anisotropic during the first few picoseconds after optical excitation. The magnitude of this anisotropy reaches its peak when the excess energy of the optically excited electrons approaches the threshold for the intervalley transfer. It has also been found that when the electrons are excited near the threshold energy for the intervalley transfer, the component of the transient photocurrent directed along the dc field for a short time after the end of the femtosecond optical pulse can become negative. The anisotropy of the transient photoconductivity has been investigated experimentally on (001) InGaAs sample by the optical pump - terahertz-probe technique. Optically induced changes in terahertz pulse amplitude were found to be dependent on the direction of terahertz field relative to the polarization of the optical pump pulse and to the crystallographic axesmore » of the semiconductor. Experimental data have been explained in terms of the transient anisotropic photoconductivity and correlate with the results of the Monte Carlo simulation.« less
Authors:
; ;  [1] ;  [2]
  1. Center for Physical Sciences and Technology, A. Gostauto 11, 01108 Vilnius (Lithuania)
  2. Institute of Physics, National Academy of Sciences of Belarus, Nezalezhnasti ave., 68, 220072 Minsk (Belarus)
Publication Date:
OSTI Identifier:
22278022
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 7; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANISOTROPY; COMPUTERIZED SIMULATION; CRYSTAL STRUCTURE; ELECTRIC FIELDS; ELECTRON MOBILITY; ELECTRONS; ENERGY DEPENDENCE; EXCITATION; GALLIUM ARSENIDES; INDIUM ARSENIDES; LASER RADIATION; MONTE CARLO METHOD; PHOTOCONDUCTIVITY; POLARIZATION; SEMICONDUCTOR MATERIALS; THRESHOLD ENERGY; TRANSIENTS