Origin and Appearance of Defective Pits in the Gate-Drain Region during Reliability Measurements of AlGaN/GaN High-Electron-Mobility Transistors on Si

摘要

The reliability of AlGaN/GaN high-electron-mobility transistors (HEMTs) on Si has been investigated using step-stress measurement and examined using scanning electron microscopy and atomic force microscopy. The illumination spots formed were confirmed to be pits with a depth of 100 nm. These pits formed at the drain-edge were found to increase and migrate towards the gate-edge for higher drain-stress voltages. The off-state breakdown voltage confirms the increase in source and substrate leakage currents dominating the device breakdown in addition to the gate leakage current. The nature and depth of pits reveals that the influence of i-GaN buffer cannot be excluded in reliability degradation.