Improved formal passivations of pseudomorphic high electron mobility transistors

Temperature-dependent characteristics of high electron mobility transistors (HEMTs) with sulfur and SiN_x passivations are comprehensively studied and demonstrated. Experimentally, for the studied device with formal passivations, better DC and microwave characteristics are obtained over wide operating temperature range. In particular, as compared with the device only with sulfur passivation, the slightly degradations of device performance are caused by the temperature stress during the deposition of SiN_x layer and presence of surface traps at the SiN_x/AlGaAs interface. Based on these good results, the formal-passivated HEMT is expected to exhibit relatively better long-term operation stability and reliable device characteristics.