A theoretical study of differing active region doping profiles for W-band (75-110 GHz) InP Gunn diodes

InP Gunn diodes are widely used as high power microwave sources in the W-band frequency range (75-110 GHz), but interesting questions remain as to the optimal active region doping profile for such devices. In this paper we carry out a detailed theoretical study, using Monte Carlo simulations, of three types of doping profiles: (i) uniform doping, (ii) graded doping (i.e. increasing linearly from cathode to anode) and (iii) notch doping (a lightly doped region adjacent to the cathode). By studying the effects of varying all the relevant parameters, such as doping levels, active region length, bias levels and temperature, under both DC and RF conditions, we argue that the notch doping approach is superior, offering high performance combined with a greater tolerance to doping fluctuations.