Surface nitridation for improved dielectric/III‐nitride interfaces in GaN MIS‐HEMTs

Effective interface engineering techniques in III‐nitride heterojunction power devices, aiming at yielding high V TH stability in insulated‐gate devices and suppressed current collapse in high‐voltage switching operation, are of critical significance to enhance device performance and reliability. In this work, we present an interface enhancement technology featuring in situ low‐damage NH 3 /Ar/N 2 pre‐gate plasma treatment prior to the ALD‐Al 2 O 3 deposition for high‐performance III‐nitride MIS‐HEMTs. It is manifest that this technology can effectively remove the native oxide while forming a monocrystal‐like nitridation interfacial‐layer (NIL) on the III‐nitride surface. The Al 2 O 3 (NIL)/GaN/AlGaN/GaN MIS‐heterostructures with high‐quality interface exhibit well‐behaved electrical characteristics, including a small subthreshold swing of ∼64 mV/dec, a small hysteresis of ∼0.09 V, tiny f/T dispersions in the C – V characteristics, and low interface trap density of ∼1 × 10 12 –6 × 10 12 cm −2 eV −1 . Cross‐sectional TEM micrograph of the Al 2 O 3 /III‐nitride gate stack with a monocrystal‐like nitridation interfacial‐layer (NIL).