Microwave electronics device applications of AlGaN/GaN heterostructures

One thrust in the recent AlGaN/GaN based HFET development hinges on the use of SiC substrates for the growth of the AlGaN/GaN heterostructures. We have achieved G_m and maximum drain current (I_max) as high as 222 mS mm^-1 and 1.71 A mm^-1 for HFETs grown on n-SiC. The HFETs on p-SiC have also shown G_m and I_max of 230 mS mm^-1 and 1.43 A mm^-1. These devices exhibited cut-off frequency (f₁) and frequency of oscillation (f_max) of 55 and 56 GHz for HFETs on p-SiC, further demonstrating the applicability of AlGaN/GaN-based HFETs in high power microwave frequency range. The availability of high quality AlGaN/GaN heterostructure has also permitted the implementation of such new device concept as metal-insulator-semiconductor FETs (MISFETs). Our MISFETs have shown low gate leakage in ± 6 V gate bias range with G_m as high as 86 mS mm^-1.