An investigation of device reliability for a micro-machined AlGaN/GaN/Si high electron mobility transistor using low frequency noise measurement

The reliability of a micro-machined AlGaN/GaN/Si high electron mobility transistor (HEMT) device is studied using drain current low frequency noise measurements for various stress conditions. After removal of the Si substrate beneath the HEMT, a high quality 300 nm layer of SiO₂ and a 20 μm copper layer are deposited to form the GaN-on-insulator structure. Compared to previous full substrate removal methods, the self-heating effect of the GaN HEMT under high current operation is overcome because there is a thick copper thermal sinking layer in the design. In addition, the traps at the buffer/transition interface are also eliminated, which is a dominant factor in device reliability after long-term stress.