Atomic Layer Deposition of Photoconductive Cu₂O Thin Films

Abstract

Herein, we report an atomic layer\ndeposition (ALD) process for\nCu₂O thin films using copper­(II) acetate [Cu­(OAc)₂] and water vapor as precursors. This precursor combination enables\nthe deposition of phase-pure, polycrystalline, and impurity-free Cu₂O thin films at temperatures of 180–220 °C. The\ndeposition of Cu­(I) oxide films from a Cu­(II) precursor without the\nuse of a reducing agent is explained by the thermally induced reduction\nof Cu­(OAc)₂ to the volatile copper­(I) acetate, CuOAc. In\naddition to the optimization of ALD process parameters and characterization\nof film properties, we studied the Cu₂O films in the fabrication\nof photoconductor devices. Our proof-of-concept devices show that\napproximately 20 nm thick Cu₂O films can be used for photodetection\nin the visible wavelength range and that the thin film photoconductors\nexhibit improved device characteristics in comparison to bulk Cu₂O crystals.