In situ capped GaN-based metal-insulator-semiconductor heterostructure field-effect transistor

In situ grown AlGaN/GaN heterostructure field-effect transistor (HFET) capped by unactivated Mg-doped GaN was demonstrated. With 1-μm-long gate length at drain-voltage of 10V, the presented HFET exhibited a drain-source current in saturation (I_DSS) of 735 mA/mm and a peak transconductance (g_m(max)) of 170 mS/mm, while the current gain cut-off frequency (f_T) and maximum frequency of oscillation (f_max) were 20.5 and 33.3 GHz, respectively. In addition, our HFET delivers 3.3 W/mm output power density with 10.3 dB power gain and 53% power-added efficiency. It is of great potential to high frequency and high power electronics applications.