Nitride-based devices fabricated by wet etching

Photo-enhanced chemical (PEC) wet etching technology was used to etch GaN and AlGaN epitaxial layers. Figure 1 shows PEC etch rate for the GaN and Al/sub x/Ga/sub 1-x/N epitaxial layers in aqueous KOH and H/sub 3/PO/sub 4/ solutions. It was found that the maximum etch rates were 510 nm/min, 1960 nm/min, 300 nm/min and 0 nm/min for GaN, Al/sub 0.175/Ga/sub 0.825/N, Al/sub 0.23/Ga/sub 0.77/N and Al/sub 0.4/Ga/sub 0.6/N, respectively. Nitride-based Schottky diodes and heterostructure field effect transistors (HFETs) were also fabricated by PEC wet etching. As shown in figures 2, 3 and 4, it was found that we could achieve a saturated I/sub D/ larger than 850 mA/mm and a maximum g/sub m/ about 163 mS/mm from PEC wet etched HFET with a 0.5/spl mu/m gate length. Compared with dry etched devices, the leakage currents observed from the PEC wet etched devices were also found to be smaller.