On the possibility of p-type doping in barium stannate

Abstract

The combination of optical transparency and bipolar dopability in a single material would revolutionize modern opto-electronics. Of the materials known to be both p- and n-type dopable (such as SnO and CuInO2), none can satisfy the requirements for both p- and n-type transparent conducting applications. In the present work, perovskite BaSnO3 is investigated as a candidate material: its n-type properties are well characterized, with La-doping yielding degenerate conductivity and record electron mobility, while it has been suggested on a handful of occasions to be p-type dopable. Herein, group 1 metals Li, Na, and K and group 13 metals Al, Ga, and In are assessed as p-type acceptor defects in BaSnO3 using a hybrid density functional theory. It is found that while K and In can induce hole concentrations up to 1016 cm−3, the low energy oxygen vacancy pins the Fermi level in the bandgap and ultimately prevents metallic p-type conductivity being achieved in BaSnO3. Nevertheless, the predicted hole concentrations exceed experimentally reported values for K-doped BaSnO3, suggesting that the performance of a transparent p–n homo-junction made from this material could be significantly improved.