Electron momentum relaxation time and mobility in a free‐standing quantum well

Autor: V. Aristov, Vladimir Mitin, N. A. Bannov
Rok vydání: 1995
Předmět:
Zdroj: Journal of Applied Physics. 78:5503-5510
ISSN: 1089-7550
0021-8979
Popis: Kinetic characteristics of the electron transport in a free‐standing quantum well are studied theoretically. The quantization of acoustic phonons in a free‐standing quantum well is taken into account and electron interactions with confined acoustic phonons through the deformation potential are treated rigorously. The kinetic equation for the electron distribution function is solved numerically for nondegenerate as well as degenerate electron gases and the electron momentum relaxation time and the electron mobility are obtained. At high lattice temperatures the electron momentum relaxation time is very similar to that obtained in the test particle approximation. Its dependence on the electron energy has steps which occur at the threshold energies for the dilatational phonons because an additional electron scattering by the corresponding acoustic phonon becomes important. The first mode makes the main contribution to the electron scattering, the contributions of the zeroth and the second modes are also important, the third and the higher modes practically unnoticeable for the studied electron concentrations and quantum well width. At lattice temperatures lower than the energy of the first dilatational acoustic mode the electron momentum relaxation time dependence on energy has additional peaks (in comparison with the test particle approximation) associated with electron scattering by several lowest acoustic phonon modes. These peaks occur near the Fermi energy in the degenerate case and in the energy range of the first dilatational modes in the nondegenerate case. They are especially pronounced for the degenerate electron gas. The temperature dependence of the electron mobility is similar to that described by the Bloch‐Gruneisen formula, however we obtained a smaller negative exponent in the low temperature region.
Databáze: OpenAIRE
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