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

摘要

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 (Lgd). Our approach is based on improving the total thickness (¿tot) of the AlGaN/GaN epi-layers as high as 9 ¿m 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 (7but) and substrate (7sub) to enhance the breakdown. For a small gate-drain spacing of Lgd = 3 ¿m we achieved a high three terminal off breakdown (3TBV) of 403 V. A very high breakdown of 1813 V was achieved across 10 ¿m electrode spacing on 2 ¿m i-GaN grown on 7 ¿m thick buffer. Further, we have identified the leakage path which triggers the breakdown of AlGaN/GaN HEMTs.