Electrical and chemical characterization of W1-x-ySixNy (0⩽x⩽0.42, 0⩽y⩽0.30) Schottky diodes for self-aligned gate GaAs MESFETs

WSiN Schottky diodes on GaAs have been electrically and chemically characterized for atomic silicon and nitrogen; compositions of 0 to 42% and 0 to 28%, respectively. It is found that the main cause for Schottky diode degradation, after high temperature annealing, is the out-diffusion of As from GaAs. For films with atomic nitrogen composition of ⩾5%, As outdiffusion is eliminated as long as the atomic Si composition is ⩽40%. WN films (5% nitrogen) were applied to the fabrication of self-aligned gate lightly doped drain MESFET´s with buried P layer. A maximum transconductance, g_m, of 370 mS/mm, f_T of 33 GHz, and DCFL inverter delay of 29 ps are measured for a 0.5 μm gate technology