AlGaN/GaN HEMT with fT:100GHz and fmax:128GHz

In this work, development of AlGaN/GaN high electron mobility transistor (HEMT) on SiC with 128 GHz maximum oscillation frequency (f_max) is reported. To achieve the desired frequency response with a robust, high yield and repeatable process, gate length (L_g) is fixed to 0.1μm and drain source spacing is set as 2μm and T-shaped gate structure is used. In order to overcome the short channel effect and increase the maximum oscillation frequency, gate recess technique is utilized. The effect of gate foot height and the SiN_x passivation layer thickness are investigated to obtain the highest possible f_max with L_g=0.1μm. As a result with a gate length of 0.1 μm AlGaN/GaN HEMT, a cut off frequency of 100GHz, and maximum oscillation frequency of 128 GHz is obtained with a drain bias of 7V.