Experimental and Theoretical Study of Alpha Particle Induced Charge Collection in GaAs FETS

An experimental angular dependence study was made of charge collection in state-of-the-art GaAs FETs. Numerical simulations of the transport of electrons in the active channel and in the semi-insulating substrate were also carried out. It is concluded that charge collected by funneling from the substrate is not significant. Both energy loss in the source and drain metallizations and degradation of the potential funneling profile at larger angles of incidence may also play major roles in the charge collection efficiency of the gate.