Developing the Ka-band GaN power HEMT devices

High quality Al_0.3Ga_0.7N/GaN/Al_0.04Ga_0.96N double heterostructure was grown by metal-organic chemical vapor deposition (MOCVD). Two kinds of fabrication technology of Ka band GaN HEMT devices were developed. Using developed 0.25 μm self-aligned T-shaped gate technology, a 4.5 W/mm output power density and 28% PAE were obtained in continues wave (CW) mode at 34GHz. To increase the frequency performance of the GaN HEMT devices, a 0.15 μm Y-shaped gate technology was developed. By using this technology, the parasitic capacitance is effectively suppressed. The fT and fmax of the GaN HEMT device fabricated with the 0.15 μm Y-shaped gate technologies were greatly improved and reached 80GHz and 110GHz, respectively. A 3.1 W/mm output power density and 26.3% PAE were also obtained in CW mode at 34GHz.