AlGaN/GaN MISHEMT analysis from an analog point of view up to 150 degrees C

Abstract

In this paper MISHEMTs with two different gate dielectrics (Al2O3 and SiNx) are analyzed focusing on some analog figures of merit like transconductance, output conductance, transistor efficiency, Early voltage and intrinsic voltage gain. The Al2O3 dielectric MISHEMT presented a degraded output characteristic in the bias range studied with a large self-heating turning the analog parameters impossible to be determined. The gate leakage of the SiN. MISHEMT is very high which degrades the subthreshold regime, decreasing the transistor efficiency at weak inversion, but the DIBL is much better than for the Al2O3 devices. The SiNx devices present much better output characteristics resulting in a relatively large Early voltage and intrinsic voltage gain in strong inversion for this kind of devices up to 84 V/V (38.5 dB). The degradation with the temperature is small (around 1.5 dB from 25 degrees C to 150 degrees C) at strong inversion operation regime.