Anisotropic hole velocity overshoot in GaAs and Si

We investigate Full Band Monte Carlo simulations of the anisotropic transient hole transport in GaAs and Si for the first time. The simulation of transient hole transport in GaAs shows that under a constant electric field of 100 kV/cm, the maximum drift velocity reaches 2.2 × 10⁷ cm/s at the room temperature, about 3 times higher than the steady-state saturation velocity. We calculated the direction dependence of the applied electric field on the hole overshoot phenomena and found that the peak velocity at the electric field applied along [100] is about 30% higher than in the case of [110], although the saturation velocities are almost the same. Simulations of Si hole transport showed a similar type of directional dependence.