Negative- U property of oxygen vacancy in cubic Hf O 2

Abstract

Oxygen vacancy in cubic Hf O2 was investigated using first-principles calculation based on density functional theory and generalized gradient approximation. Five different charge states (V++, V+, V0, V-, and V - ) were investigated. It was found that the oxygen vacancy in Hf O2 has negative- U behavior and it is energetically favorable for the vacancy to trap two electrons or two holes when the respective charges are injected into the oxide, due to large electron-lattice interaction. Therefore, oxygen vacancy is a main source of charge traps in both n - and p -type metal-oxide-semiconductor field-effect transistors based on Hf O2, and reducing such defects will be useful in limiting charge trapping and in improving the quality of the high- k dielectric in modern complementary metal-oxide semiconductor technology. © 2005 American Institute of Physics.