The preparation of CuO film under different annealing atmospheres and investigation of the excellent electrical and undoped tunable electroluminescence characteristics of Au/i-CuO/n-GaN LED

Abstract

Copper oxide (CuO) film is widely used in optoelectronic devices. The CuO films were fabricated by radio frequency (RF) magnetron sputtering and then annealed at 700 °C under different atmospheres (unannealed, O2, N2, vacuum). The physical characteristics of the films were analyzed systematically. In addition, we prepared Au/i-CuO/n-GaN metal-insulator-semiconductor (MIS) structure devices using optimized conditions. The devices had excellent rectifying characteristics at different ambient temperatures and the turn-on voltage was about 1.7 V. The working mechanism of the diode was analyzed through electroluminescence (EL) spectra and band structure. The EL spectra observed at positive and negative bias were compounded by holes and electrons on the gold electrode passing through the insulating layer into the n-GaN side. The EL spectra exhibited that a dominant ultraviolet (UV) emission peak at ∼376 nm was observed under forward bias (FB), and a strong near-white light emission peak at ∼530 nm was observed under reverse bias (RB). The device exhibited unique electroluminescent spectra tunability varying with bias conditions. The chrominance coordinate of the device under RB was (0.3067,0.3604), and the color temperature was 6585 K. This study proved the application potential of i-CuO as an insulating layer in the preparation of new reference for MIS structured GaN-based tunable light-emitting diodes.