Buffer Vertical Leakage Mechanism and Reliability of 200-mm GaN-on-SOI

A comprehensive study on buffer vertical leakage mechanism and buffer reliability of 200-mm GaN-on-SOI is conducted in this paper. The buffer vertical leakage current versus bias is found to sequentially comprise three ranges of low-field leakage, variable-range hopping, and breakdown. The low-field leakage increase at high temperatures has been proven to be dominated by surface leakage. The stressing voltages of buffer time-dependent breakdown (TDB) measurements have a significant impact on shape factor β. Stress-induced leakage current is observed in the wear-out phase of the TDB curves. Stress-and-sense measurements in this phase indicate that defects are generated probably around the threading dislocations, where more localized Joule heating and more defects are created by a positive feedback, and finally, the buffer breaks down due to thermal runway. At last, based on the Weibull plot and E-model, the operating voltage is extrapolated to be 470 V corresponding to an expected lifetime of 10 years at 175 °C, with area scaling to the drain terminal of a 150-mm power transistor and failures scaling to 0.01%. The qualification of GaN-on-SOI is crucial for future 200-V GaN power integrated circuit on this platform.