WARM AND HOT HOLE DRIFT VELOCITY IN GAAS STUDIED BY MONTE-CARLO SIMULATION

We have studied hole mobilities and drift velocities in undoped GaAs at 77 and 300 K using the Monte Carlo method. Two different sets of valence band parameters were used (V1: A = 7.98, B = 5.16, C = 6.56; V2: A = 7.65, B = 4.82, C = 7.7). The results show that the low-field mobility is sensitively dependent on the particular choice of valence band parameters. The low-field mobilities obtained were 440 cm2/V s(V1) and 330 cm2/V s(V2) at 300 K, and 17 150 cm2/V s(V1) and 11 400 cm2/V s(V2) at 77 K. The warm hole transport coefficients beta(0) and gamma(0) were extracted from the drift velocity data. At 77 K, beta(0) = - 7 x 10(-9) m2/V2 and gamma(0) was estimated to be 2 x 10(-10) m2/V2(V1). At 300 K the corresponding estimated values were - 2 x 10(-13) m2/V2 and 5 x 10(-14) m2/V2, respectively. The warm hole region is limited to E < 0.04 kV/cm at 77 K and to E < 10 kV/cm at 300 K. Anisotropy in the drift velocity is negligible in the warm hole region and relatively small at higher electric fields. Complete velocity saturation was not observed for the electric fields considered here (E < 60 kV/cm).