Carbon as a Shallow Donor in Transparent Conducting Oxides

ZnO, Ga₂O₃, and In₂O₃ are materials of increasing technological importance, with applications in power electronics and next-generation displays, but they are often contaminated with carbon impurities. Despite the commonness of carbon contamination, its effects have not previously been determined. The authors' calculations indicate that, surprisingly, in all cases carbon is incorporated at a cation (not an interstitial or oxygen) site and acts as an electron donor, contributing to background n-type conductivity. With this new insight, carbon could actually be exploited as an intentional dopant in conducting oxides.