Enhancement of transparency in epitaxially-grown p-type SnO films by surface-passivation treatment in a Na2S aqueous solution

Abstract

Abstract We report on the epitaxial growth of (001)-oriented SnO films on yttria-stabilized zirconia (100) substrates by pulsed-laser deposition and the impact of surface-passivation treatment on the optical transparency. The films immersed in a Na2S aqueous solution exhibited average visible transmittance higher than that of the as-grown ones by ∼18% despite negligibly small variations in the crystalline structure, p-type conductivity, and composition. Based on these results, the enhanced visible transmittance can be attributed to the suppression of midgap states near the film surface. The extended treatment resulted in conversion to a SnS phase, demonstrating a facile anion-exchange reaction.