Impact ionization in bulk GaAs high field domain

An investigation of impact ionization in the high field domains of GaAs Gunn effect devices has been carried out. A method of measuring the number of excess electrons generated per domain transit was developed, based on the measurement of the increase in the valley current from one domain transit to the next while impact ionization is occurring in the domain. This method was used to experimentally determine the carrier generation per domain transit as a function of excess domain potential VDfor three material carrier concentrations. These results are compared to a theoretical calculation of based upon an approximate solution of the continuity equation and invariant domain calculations. The experimental and theoretical results agree to within 2 percent for cm^-3and 6 percent for cm^-3.