Controlled oxygen vacancy induced p-type conductivity in HfO{2-x} thin films

TL;DR

This study demonstrates that controlled oxygen vacancies in HfO₂-x thin films induce p-type conductivity and significantly reduce the band gap, revealing a new defect-driven electronic behavior.

Contribution

The paper introduces a method to engineer oxygen vacancies in HfO₂-x films, establishing a link between vacancy concentration and p-type conductivity with band gap tuning.

Findings

P-type conductivity appears above a certain oxygen vacancy threshold.

Charge carrier density reaches up to 6×10^{21} cm^{-3}.

Band gap decreases by over 1 eV with increasing vacancies.

Abstract

We have synthesized highly oxygen deficient HfO$_{2-x}$ thin films by controlled oxygen engineering using reactive molecular beam epitaxy. Above a threshold value of oxygen vacancies, p-type conductivity sets in with up to 6 times 10^{21} charge carriers per cm3. At the same time, the band-gap is reduced continuously by more than 1 eV. We suggest an oxygen vacancy induced p-type defect band as origin of the observed behavior.