TCAD Investigation for Dual-Gate MISHEMT with Improved Linearity and Current Collapse for LNAs

This investigation examines the performance of AlGaN/GaN MISHEMTs having single-gate and dual-gate with different biasing combinations to explore the linearity in terms of gmpeak, gate voltage swing (GVS) and higher-order coefficients for intermodulation distortion for low-noise amplifiers (LNAs). In addition, the influence of distinct gate biasing configurations of DG-MISHEMT on current collapse (CC) (in response to OFF-state stress in drain) has been studied using TCAD simulations. It has been observed that drop in drain current value after the gate–drain voltages return to quiescent voltages (VGSQ, VDSQ) reduces for DG-MISHEMT (when both the gates are shorted together) to 9.1% as compared with 19.4% for SG-MISHEMT. Besides, the CC phenomena for DG-MISHEMTs (for shorted gates) exhibit a slight increase from 9% to 11.8% when workfunction increases from 4.1 eV to 5.2 eV for gate G2. Further, linearity in terms of GVS is observed to be doubled for AlGaN/GaN DG-MISHEMTs with both the gates connected together as compared with device with screen gate G2 shorted to source. Additionally, radio frequency performance has been studied in terms of cut-off frequencies fT and fmax and minimum noise-figure NFmin for AlGaN/GaN SG-MISHEMT and DG-MISHEMTs for different gate to gate distance i.e., LGG = 100 and 200 nm. It is observed that NFmin is minimum for AlGaN/GaN DG-MISHEMT (with gate G1 floating and gate G2 is biased and LGG = 100 nm) i.e., 1.13 dB with corresponding power gain of 18.7 dB at 50 GHz.