700-V p-GaN Gate HEMT with Low-Voltage Third Quadrant Operation Using Area-Efficient Built-in Diode

A 700-V normally-off p-GaN gate HEMT featuring area-efficient distributed built-in Schottky barrier diode (SBD) is demonstrated with low-loss reverse conduction capability. The reverse conduction voltage of the device VRC is - {2.1 V (@ I_D = -20 mA/mm). As the reverse conduction is through the built-in SBD, the low VRC of the proposed transistor is independent of the HEMT's VTH and turn-off gate bias VGS. On the contrary, the VRC of a conventional p-GaN gate power transistor is not only much higher but also strongly dependent on the VTH and OFFstate VGS. The built-in SBD elements are embedded into the HEMT's source side in a distributed fashion along the width of the device, so that the SBD and HEMT share a common access region in forward and reverse conduction, leading to reduced ON-resistance (RON) compared to the scheme with side-by-side transistor/SBD pair. The anode of built-in Schottky contact is embedded at the source side and is shielded from the high electric field by the gate field plate. Thus, the reverse leakage current of Schottky contact is well-suppressed.