High-performance vertical GaN field-effect transistor with an integrated self-adapted channel diode for reverse conduction

Abstract

A vertical GaN field-effect transistor with an integrated self-adapted channel diode (CD-FET) is proposed to improve the reverse conduction performance. It features a channel diode (CD) formed between a trench source on the insulator and a P-type barrier layer (PBL), together with a P-shield layer under the trench gate. At forward conduction, the CD is pinched off due to depletion effects caused by both the PBL and the metal–insulator–semiconductor structure from the trench source, without influencing the on-state characteristic of the CD-FET. At reverse conduction, the depletion region narrows and thus the CD turns on to achieve a very low turn-on voltage (V F), preventing the inherent body diode from turning on. Meanwhile, the PBL and P-shield layer can modulate the electric field distribution to improve the off-state breakdown voltage (BV). Moreover, the P-shield not only shields the gate from a high electric field but also transforms part of C GD to C GS so as to significantly reduce the gate charge (Q GD), leading to a low switching loss (E switch). Consequently, the proposed CD-FET achieves a low V F of 1.65 V and a high BV of 1446 V, and V F, Q GD and E switch of the CD-FET are decreased by 49%, 55% and 80%, respectively, compared with those of a conventional metal–oxide–semiconductor field-effect transistor (MOSFET).