D.C. Computer Simulation of GaAs DAR Impatt Suitable for MM Wave

Abstract

Computer simulation of d.c. field and current density profiles of a GaAs Double Avalanche Region (DAR) Impatt diode has been carried out considering realistic variation of ionization rates and drift velocities of electrons and holes with applied electric field. It is found that for the structure n+—p—v—n—p+ under reverse breakdown condition, the field shows two peaks at the edge of the depletion layer as in the case of Si-DAR Impatt. But unlike Si, the left edge peak is larger than the right edge peak. Space charge cancellation is also prominent in GaAs. Further, avalanche layers are found to be limited to 0.1 μ and there is no widening of avalanche and drift zones with the increase of current density. GaAs shows better results than Si in respect of variation of ionization rates and field versus distance. It is concluded that GaAs DAR Impatt will be more efficient and powerful device in the mm wave range compared to Si DAR Impatt.