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

Journal Article · Fri Feb 21 00:00:00 EST 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4865961· OSTI ID:22278022

Adomavičius, R.; Krotkus, A. ^[1]; Malevich, V. L. ^[2]

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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)

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 axes 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.

• OSTI ID: 22278022
• Journal Information: Journal of Applied Physics, Vol. 115, Issue 7; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

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