Designing of double gate HEMT in TCAD for THz applications

The terrific carrier transport properties of III-V compound semiconductors have attraction for THz applications due to outstanding high-frequency characteristics. III-V HEMTs based on InGaAs/InAlAs have emerged as particularly promising for high frequencies applications. In this paper, we present two-dimensional (2-D) HEMTs structures based on InAlAs/ InGaAs using Silvaco TCAD software. Two types of HEMT structures were focused to enhance the frequency of operation: a) conventional single gate HEMT (SGHEMT) structure, and b) double gate HEMT (DGHEMT) structure. In SGHEMT devices, two different gate lengths (300 and 100nm) were studied while DGHEMT device was designed with 50nm gate length. In SGHEMT devices, f_max is increased from 349 to 432 GHz by the reduction in gate length. Similarly, f_T is increased from 108 to 144 GHz. Hence, 33% enhancement in cut-off frequency is achieved. For further enhancement in frequency, DGHEMT structure is implemented to increase the cut-off frequency upto 175 GHz.