Improved electrical characteristics of Ge nMOSFET with suitable nitrogen content in starting interfacial layer

Abstract

The realization of Ge n-channel MOSFETs (nMOSFET) encounters many challenges, such as poorer interface quality and thermal stability, in comparison with Ge p-channel MOSFETs. Since the oxygen vacancy and interface trap in gate dielectric can be effectively passivated by a nitrogen incorporation, a germanium oxynitride (GeON) starting interfacial layer with suitable nitrogen content was proposed to improve the interface quality of Ge nMOSFETs in this work. A low equivalent oxide thickness of ~0.6 nm, a low gate leakage current of ~6 × 10−4 A/cm2, and a low subthreshold swing of ~120 mV/dec in Ge nMOSFET can be simultaneously achieved by incorporating a nitrogen content of ~20.4% in the GeON starting interfacial layer.