Enhancing the breakdown voltage by growing 9 µm thick AlGaN/GaN HEMTs on 4 inch silicon

We have designed a high breakdown yielding AlGaN/GaN HEMTs on 4 inch silicon wafer without using a field plate or increasing the gate-drain length (L_gd). Our approach is based on improving the total thickness (T_gd) of the AlGaN/GaN epi-layers as high as 9 μm which improves the quality of i-GaN. Growing i-GaN on thick buffer reduces the dislocation density, increases the resistance between the surface electrode and Si substrate which considerably suppresses the leakage through buffer (I_buf) and substrate (I_sub) to enhance the breakdown. For a small gate-drain spacing of L_gd = 3 μm we achieved a high three terminal off breakdown (3TBV) of 403 V. A very high breakdown of 1813 V was achieved across 10 μm electrode spacing on 2 μm i-GaN grown on 7 μm thick buffer. Further, we have identified the leakage path which triggers the breakdown of AlGaN/GaN HEMTs.