1.4 kV breakdown voltage for MOCVD grown AlGaN/GaN HEMTs on Si substrate

The growth of GaN transistors on Si substrate has received tremendous attention due to large size availability of Si substrates at low cost. However, it is imperative to demonstrate a high breakdown AlGaN/GaN HEMTs on Si grown by MOCVD as high power device applications are the primary significant contribution expected of a GaN based devices. In the past, we have demonstrated high breakdown on AlGaN/GaN HEMTs grown on Si by thickening the buffer layers [1-2]. All our previous reports were based on the 3-terminal OFF breakdown voltage (3TBV) measured on devices with short gate-drain (L_gd = 3 or 4 μm) spacing which limited the breakdown voltage due to Schottky gate leakage current [3]. Therefore, in the current investigation, we prepared HEMTs with various L_gd and studied its dependence on 3TBV. We observed a 3TBV of 1.4 kV for an AlGaN/GaN HEMT grown on Si having L_gd of 20 μm.