Stable high power GaN-on-GaN HEMT

High power AlGaN/GaN HEMTs on free-standing GaN substrates with excellent stability have been demonstrated for the first time. When operated at a drain bias of 50V, devices without a field plate showed a record CW output power density of 10.0W/mm at 10GHz with an associated power-added efficiency of 45%. The efficiency reaches a maximum of 58% with an output power density of 5.5W/mm under a drain bias of 25V at 10GHz. Long-term stability of device RF operation was also examined. Under ambient conditions, devices biased at 25V and driven at 3dB gain compression remained stable at least up to 1,000 hours, degrading only by 0.35dB in output power. Such results clearly demonstrate the feasibility of GaN-on-GaN HEMT as an alternative device technology to the GaN-on-SiC HEMT in supporting reliable, high performance microwave power applications.