Electron trapping at the high-κ/GeO₂ interface: The role of bound states

Passivation of the germanium interface using native oxide results in a potential well at the interface of GeO₂ and high-κ dielectric for n-channel metal-oxide-semiconductor field effect transistors. The well forms a potential trapping site for electrons, which could result in threshold voltage instability. We present calculations for the bound states and their occupancy in the well. The significance of threshold voltage shift in an 8-nm node field effect transistor and those with larger dimensions is investigated. The main conclusion is that charge storage in the well is insignificant at the 8-nm technology node but can have a significant effect on larger devices.