Five-valley model for the study of electron transport properties at very high electric fields in GaAs

A Monte Carlo method has been developed for the study of electron transport properties (drift velocity, average energy, electron ionization coefficient, etc.) in GaAs for high fields (100-600 kV cm -1 ), using a five-valley conduction band model. To the three valleys traditionally used ( Gamma 6 , L 6 , X 6 ) two others have been added (X 7 , Gamma 7 ) that belong to conduction subbands above the first one. The model is shown to be also valid for the study of transport when a low electric field is applied (0-100 kV cm -1 ). The results highlight the importance of the X 7 valley of the second conduction subband in high field transport phenomena, and are compared with different experimental values.