On the dc and noise properties of the gate current in epitaxial Ge p-channel metal oxide semiconductor field effect transistors with TiN∕TaN∕HfO2∕SiO2 gate stack

Abstract

In this paper, we report the dc and noise properties of the gate current in epitaxial Ge p-channel metal oxide field effect transistors (pMOSFETs) with a Si passivated surface. The gate stack consists of HfO2∕SiO2 dielectric with TiN∕TaN metal gate. The observed temperature dependence of the gate current indicates that the dominant charge transport mechanism through the gate dielectric consists of Poole–Frenkel conduction. Gate current 1∕f noise is more than two orders higher in the case of Ge pMOSFETs when compared to reference Si pMOSFETs. Ge outdiffusion into the gate oxide is the suspected cause for the enhanced Poole–Frenkel conduction and the high gate current 1∕f noise in Ge pMOSFETs.