Nitride-based Schottky diodes and HFETs fabricated by photo-enhanced chemical wet etching

Photo-enhanced chemical (PEC) wet etching technology was used to etch GaN and AlGaN epitaxial layers. It was found that the maximum etch rates were 510, 1960, 300, and 0nm/mm for GaN, Al_0.175Ga_0.825N, Al _0.23Ga_0.77N, and Al_0.4Ga_0.6N, respectively. It was also found that we could achieve a high Al _0.175Ga_0.825N to GaN etch rate ratio of 12.6. Nitride-based Schottky diodes and heterostructure field effect transistors (HFETs) were also fabricated by PEC wet etching. It was found that we could achieve a saturated I_D larger than 850mA/mm and a maximum g _m about 163mS/mm from PEC wet etched HFET with a 0.5μm gate length. Compared with dry etched devices, the leakage currents observed from the PEC wet etched devices were also found to be smaller.