Improved electrical properties of Ge p-MOSFET with HfO 2 gate dielectric by using TaO xN y interlayer

摘要

The electrical characteristics of germanium p-metal-oxide-semiconductor (p-MOS) capacitor and p-MOS field-effect transistor (FET) with a stack gate dielectric of HfO 2TaO xN y are investigated. Experimental results show that MOS devices exhibit much lower gate leakage current than MOS devices with only HfO 2 as gate dielectric, good interface properties, good transistor characteristics, and about 1.7-fold hole-mobility enhancement as compared with conventional Si p-MOSFETs. These demonstrate that forming an ultrathin passivation layer of TaO xN y on germanium surface prior to deposition of high- k dielectrics can effectively suppress the growth of unstable GeO x, thus reducing interface states and increasing carrier mobility in the inversion channel of Ge-based transistors. © 2008 IEEE.