The effect of ohmic contact location on the buffer leakage current of AlGaN/GaN
heterostructure was investigated and the AlGaN/GaN HEMT employing the proposed ohmic
contact pattern was fabricated. We have fabricated 3 different types of ohmic patterns; type A - both
contacts are on the etched GaN buffer layer, type B - one is on the etched GaN buffer layer and the
other is on the unetched GaN cap layer and type C - both contacts are on the unetched GaN cap
layer. Our experimental results showed that the ohmic contact on GaN buffer increased the buffer
leakage current due to the lateral diffusion of ohmic metals. The proposed AlGaN/GaN HEMT
successfully decreased the leakage current and did not affect the forward drain current and the
transconductance.
Effect of different ohmic contact pattern on GaN HEMT electrical properties