Temperature and Gate-Length Dependence of Subthreshold RF Detection in GaN HEMTs

The responsivity of AlGaN/GaN high-electron mobility transistors (HEMTs) when operating as zero-bias RF detectors in the subthreshold regime exhibits different behaviors depending on the operating temperature and gate length of the transistors. We have characterized in temperature (8-400 K) the detection performance of HEMTs with different gate lengths (75-250 nm). The detection results at 1 GHz can be reproduced by a quasi-static model, which allows us to interpret them by inspection of the output I-D - V-DS curves of the transistors. We explain the different behaviors observed in terms of the presence or absence of a shift in the zero-current operating point originating from the existence of the gate-leakage current jointly with temperature effects related to the ionization of bulk traps.

Automated summary

The responsivity of AlGaN/GaN high-electron mobility transistors (HEMTs) as zero-bias RF detectors in the subthreshold regime varies depending on the operating temperature and gate length. By characterizing the detection performance of HEMTs with different gate lengths (75-250 nm) at temperatures ranging from 8 K to 400 K, we found that the different behaviors observed can be explained by the presence or absence of gate-leakage current and temperature effects related to the ionization of bulk traps.