Estimation of Short Circuit Capability of GaN HEMTs Using Transient Measurement

Wafer level transient voltage measurement (WLTVM) to estimate the short circuit capability of AlGaN/GaN HEMT devices is suggested. Two groups of samples with similar DC and switching properties but different short circuit capabilities of 4-7 and > 10μs were evaluated. The extracted junction temperature and the measured saturation/linear current under repeated short circuit stresses suggest that the short circuit failure is attributed to the degradation in the drift region. The WLTVM could measure the transient potential change along the drift region during short circuit condition. The sample with lower short-circuit survivability showed a faster propagation of the high field traveling from the gate to the drain. The time the high electric field reaches the drain coincides with the time of the short circuit failure. In addition to providing the insight into the short circuit failure mechanism, wafer-level method can provide a quick and non-destructive evaluation of the short circuit capability before packaging devices.