In0.52Al0.48As/In0.53Ga0.47As higfets using novel 0.2 μm self-aligned T-gate technology

0.2μm self-aligned T-gate InAlAs/InGaAs HIGFET’s have been fabricated and investigated experimentally. The submicron gate technology is based on lift-off of sputtered WSi_x. Low gate leakage current and high gate/drain breakdown were obtained with the help of a T-gate structure which controls the lateral spreading of the source/drain implants. The peak extrinsic g_m is 650 mS/mm and g_ds shows a low value of 35 mS/mm using a p-buffer design. The DC gain ratio (g_m/ g_ds) is much higher (~18) with a p-buffer than with an undoped buffer approach where the ratio is only 4. The short-channel effects associated with substrate injection are also substantially reduced using the p-doped buffer design.