Low-Temperature Measurements on Germanium-on-Insulator pMOSFETs: Evaluation of the Background Doping Level and Modeling of the Threshold Voltage Temperature Dependence

摘要

Fully depleted GeOI (Germanium on Insulator) pMOSFETs with HfO_2/TiN gate stack and Si-passivation are studied at low temperature. The impact of the starting Ge material and N-type channel doping on threshold voltage is examined. As there is no evidence of a background doping in Ge films, the typical parasitic conduction and threshold voltage shift in p-channel GeOI MOSFETs are due to interface states. An extended model predicting the threshold voltage temperature dependence in GeOI transistors is proposed.