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

• Published in: Physica status solidi. A, Applications and materials science Applications and materials science, 2015-05, Vol.212 (5), p.1059-1065
• Main Authors: Chen, Kevin J., Yang, Shu, Tang, Zhikai, Huang, Sen, Lu, Yunyou, Jiang, Qimeng, Liu, Shenghou, Liu, Cheng, Li, Baikui
• Format: Article
• Language: English
• Subjects: Aluminum gallium nitrides; Aluminum oxide; Density; Devices; Formations; Gallium nitrides; III-nitride; interface engineering; MIS-HEMTs; nitridation interfacial-layer; Oxides; Switching; VTH instability
• ISSN: 1862-6300; 1862-6319
• DOI: 10.1002/pssa.201431712

Effective interface engineering techniques in III‐nitride heterojunction power devices, aiming at yielding high VTH 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 NH3/Ar/N2 pre‐gate plasma treatment prior to the ALD‐Al2O3 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 Al2O3(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 × 1012–6 × 1012 cm−2eV−1. Cross‐sectional TEM micrograph of the Al2O3/III‐nitride gate stack with a monocrystal‐like nitridation interfacial‐layer (NIL). With in situ low‐damage native oxide removal, nitrogen vacancy compensation, and the formation of a monocrystal‐like nitridation interfacial‐layer (NIL) with Al‐N bonds, a high‐quality Al2O3/GaN‐cap interface has been obtained in the Al2O3(NIL)/GaN/AlGaN/GaN MIS‐HEMTs. It is validated that the NIL is capable of preventing the formation of detrimental Ga‐O bonds and enabling the realization of high‐performance III‐N based MIS‐HEMTs that are highly desirable in power switching applications.