Influence of Oxygen Plasma on the Growth, Structure, Morphology, and Electro-Optical Properties of p-Type Transparent Conducting CuBr Thin Films

Abstract

p-type transparent conducting CuBr thin films were grown by thermal evaporation of CuBr followed by oxygen plasma treatment. Efficient incorporation of oxygen into the CuBr films was revealed, and the influence of plasma exposure on the electrical, structural, optical, and electronic properties of CuBr films was investigated. X-ray diffraction (XRD) analysis indicated the Zincblende structure of the oxygen plasma treated CuBr (OCB) films with the formation of nanocrystalline grains preferentially oriented along the (111) direction. p-type conducting OCB films show >85% average transmittance along with hole concentration, conductivity and Hall mobility values of ∼1019 cm–3, ∼1.5 S cm–1 and ∼0.45 cm2 V–1 s–1, respectively. The X-ray photoelectron spectra of the OCB films demonstrated that the plasma exposure resulted in a significant increase in the O 1s signal at the surface of OCB films. On the basis of the experimental results from the Hall measurements and X-ray photoemission, a possible explanation comprising the formation of a surface CuO layer is also proposed to elucidate the increase in the p-type conductivity of the OCB films. Strong room temperature emission of OCB films at around 416 nm was also observed, the intensity of which decreased with the increase of oxygen plasma exposure time. The results present oxygen plasma exposure as a simple and promising technique for the production of CuBr-based p-type materials for future transparent electronics.