Packaging and high-temperature characterization of a 650 V, 150 A eGaN HEMT

Among the salient features of gallium nitride (GaN) power semiconductor devices is their high-temperature capability. However, commercial GaN devices, such as the high-electron-mobility transistors (HEMTs), are limited to 125 °C junction-temperature operation because of their packaging. To explore the high-temperature capability of GaN power devices, a commercial 650 V, 150 A enhancement-mode GaN HEMT chip was packaged by silver-sintering die-bonding on direct-bond-copper substrate and encapsulation in a high-temperature polymer enclosure filled with nitrogen. Static characteristics of the packaged GaN device were measured at temperatures up to 250 °C. The threshold voltage of the transistor at 250 °C decreased to around 0.9 V, about 30% lower than that at room temperature. At temperatures beyond 150 °C, the saturation current fell sharply below the rated current, resulting in a rapid rise in the on-resistance versus current. At 250 °C, the saturation current decreased rapidly to around 67 A, <45% of the rated current. The reverse leakage also increased sharply at temperatures beyond 150 °C. Although the packaged device was operational at 250 °C, one would need to significantly lower the expectations for its performance and address the challenges of packaging and thermal management if it were to be used in a high-temperature power converter. (paper)