High-Temperature Performance of AlGaN/GaN MOSHEMT With $\hbox {SiO}_{2}$ Gate Insulator Fabricated on Si (111) Substrate

The dc operation of high-quality AlGaN/GaN metal–oxide–semiconductor high-electron-mobility transistors (MOSHEMTs) on Si (111) substrates, fabricated using $\hbox {SiO}_{2}$ as the gate insulator, is investigated for the first time as a function of ambient temperature $(T)$ . $I$ – $V$ and $C$ – $V$ characteristics of these depletion-mode devices are studied in the temperature range of 25–200 $^{\circ}\hbox {C}$ , and the results are compared to those of reference AlGaN/GaN HEMTs processed on the same wafer and of identical geometry. For devices with an 8- $\mu\hbox {m}$ drain-to-source separation and $\hbox {1} \times \hbox {2.5} \times \hbox {100} \mu \hbox {m}^{2}$ gate dimensions, the maximum output current density was about 730 mA/mm at $+$ 2 V gate bias for both types of transistors. The thermal behavior of the MOSHEMTs on Si was found to resemble that of devices grown on sapphire and silicon carbide with the gate leakage current exhibiting a rapid increase with $T$ but remaining below the levels seen in the reference HEMTs. The maximum drain current also showed a relatively smaller degradation at elevated temperatures as compared to previously published data.