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

In this paper MISHEMTs with two different gate dielectrics (Al
₂
O
₃
and SiN
_x
) are analyzed focusing on some analog figures of merit like transconductance, output conductance, transistor efficiency, Early voltage and intrinsic voltage gain. The Al
₂
O
₃
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
_x
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 Al
₂
O
₃
devices. The SiN
_x
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 °C to 150 °C) at strong inversion operation regime.