Diffusion of hot carriers in two-valley semiconductors

Abstract

An analytical Green function approach to the calculation of the diffusion coefficient of hot electrons in two-valley semiconductors at high electric fields is presented. Correlation functions for velocity fluctuation and population fluctuation are derived, respectively, to determine the thermal fluctuation term and carrier transfer term of the diffusion coefficient. New terms related to those cross-correlation functions for the velocity and population are introduced. Reasonable agreement between calculated and measured diffusion coefficients is obtained when the method is applied to n-type GaAs at room temperature.