Electroluminescence of γ-CuBr thin films via vacuum evaporation depositon

Abstract

γ-CuBr is a I–VII wide band gap mixed ionic–electronic semiconducting material with light emitting properties suitable for novel UV/blue light applications. Its structural and physical properties allow for vacuum deposition on a variety of substrates and herein we report on the deposition of γ-CuBr on Si and indium tin oxide coated glass substrates via vacuum evaporation with controllable film thickness from 100 to 500 nm. Temperature dependent photoluminescence characteristics of these γ-CuBr films on Si (1 0 0) reveal familiar Zf and I1 excitonic features. A thin film electroluminescent device using a γ-CuBr active layer was fabricated and room temperature electroluminescence was obtained for γ-CuBr for the first time. CuBr features relating to known excitonic (Zf, 3.1 eV) emissions were observed as well as a number of previously unknown emissions at 3.81, 3.02, 2.9, 2.75 and 2.1 eV. We speculate on the origins of these peaks and attribute them to the presence of monovalent Cu+ generated during ac excitation.