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

摘要

Effective interface engineering techniques in Hi-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_2O_3 deposition for high-performance m-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 m-nitride surface. The Al_2O_3(NIL)/GaN/AlGaN/GaN MIS-heterostructures with high-quality interface exhibit well-behaved electrical characteristics, including a small subthresh-old 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_2O_3/Ⅲ-nitride gate stack with a monocrystal-like nitridation interfacial-layer (NIL).