NEW PROCESSING METHODS FOR N-GAAS FIELD-EFFECT TRANSISTORS USING NEUTRALIZATION OF SHALLOW DONORS BY HYDROGEN AND DISSOCIATION PROCESS BY UV-LIGHT

An original process is presented for fabricating GaAs field effect tra nsistors. This process is based on the neutralisation of shallow donor s by atomic hydrogen diffused in a highly doped and thin GaAs:Si epila yer and on the reactivation of particular hydrogenated zones by exposu re to UV Tight. Using these new techniques, we have studied the perfor mance of field effect transistors when their source and drain access r esistances are gradually decreased. Initial hydrogenated FETs show ver y encouraging characteristics. For a gate length of 0.3 mu m, typical transconductances are 800mS/mm with cutoff frequencies > 70GHz.