Monte Carlo calculations of hot-electron transient behaviour in CdTe and GaAs

Changes of electron mean energy, drift velocity, and valley occupation due to rectangular pulses of spatially uniform electric field are calculated for GaAs and CdTe at 300 and 77 K. The models include two types of spherical valley; non-parabolicity of the central ones is approximated as suggested by Kane. Simultaneous motion of many electrons in the conduction band is simulated by a Monte Carlo procedure, which takes into account intravalley acoustic and polar optical scattering and phonon-assisted electron transitions between the valleys. Relaxation of energy is slower in CdTe as compared to GaAs. However, the accepted models predict that if the electric field ensures the same steady occupation of the satellite valleys in both the crystals the transient processes following the application of field are shorter in CdTe despite of higher energy separation of the valleys. When the field is off the satellite valleys of CdTe get empty faster, too.