Gate-Metal Formation-Related Kink Effect And Gate Current On In0.5al0.5as/In0.5ga0.5as Metamorphic High Electron Mobility Transistor Performance

In0.5Ga0.5As/In0.5Al0.5As metamorphic high electron mobility transistos were fabricated with different gate-metal formations: mesa type or air type and without or with a buried gate. Only air-type devices with a buried gate show no kink effect. Experimental results indicate that gate-feeder metal and annealing process give effects on gate current and noise figure. The peak gate current of 12 (120)mu A/mm for air-type (mesa-type) devices before annealing is improved to 8 (55)mu A/mm after annealing. At 1.8 GHz, associated gain of 25 dB is obtained at F-min=1.24 dB for air-type devices after annealing, while 23 dB is obtained at F-min=1.25 dB before annealing. (c) 2006 American Institute of Physics.