A study of output power stability of GaN HEMTs on SiC substrates

Gallium Nitride (GaN) HEMTs are the focus of intense research and development due to their potential for the realization of power amplifiers (PAs) with high gain and record levels of power delivery. Much of the work in GaN HEMT development has been concentrated on performance improvement, and the demonstration of exceedingly higher power densities (>10W/mm). To demonstrate this performance, the device is typically subjected to bias levels greater than 40V, which result in large electric field stresses in the vicinity of the gate. Additionally, junction temperatures greater than 250°C are predicted for the corresponding density of dissipated power. There is a lack of a comprehensive understanding of the effect of these large electrical and thermal stresses on the aging and degradation of GaN devices. There has only been a limited number of reports on the stability of GaN devices over time under RF dirve. In the present paper, we investigate the stability of GaN/AlGaN HEMTs under RF and DC stress. We provide a first look at the behavior of the device output power, quiescent currents, and leakage currents as a function of time under variable RF and DC stress conditions.