Fermi level pinning by defects in HfO2-metal gate stacks

Abstract

Various mechanisms for the Fermi level pinning of p-gate metals on HfO2 are analyzed in detail. It is found that for Fermi energies below the Si valence band, HfO2 can oxidize Si by creating positively charged O vacancies. The band bending due to this vacancy concentration can account for the observed Fermi level pinning of p metals on HfO2.