Attracting shallow donors: Hydrogen passivation in (Al,Ga,In)-doped ZnO

TL;DR

This study uses first principles calculations to reveal that hydrogen and shallow donors in ZnO form complexes, which can limit the material's n-type conductivity.

Contribution

It demonstrates that shallow donors and hydrogen in ZnO attract and form complexes, contrary to expectations, affecting conductivity.

Findings

Hydrogen and shallow donors form complexes in ZnO.

Complex formation leads to deeper donor levels.

This limits n-type conductivity in doped ZnO.

Abstract

The hydrogen interstitial and the substitutional Al_Zn, Ga_Zn and In_Zn are all shallow donors in ZnO and lead to n-type conductivity. Although shallow donors are expected to repel each other, we show by first principles calculations that in ZnO these shallow donor impurities attract and form a complex, leading to a donor level deep in the band gap. This puts a limit on the n-type conductivity of (Al,Ga,In)-doped ZnO in the presence of hydrogen.