Fabrication of transparent p-CuI/n-ZnO heterojunction with excellent ideality factor

Copper iodide (CuI) is an intrinsically transparent p-type semiconductor with a wide band gap of about 3.1 eV. In this work, Cu3N films were prepared as precursors through high-power impulse magnetron sputtering and then were solid-phase iodinated at room temperature for the preparation of transparent CuI films. Subsequently, transparent p-CuI/n-ZnO heterojunctions were fabricated wherein ZnO layers were deposited by radio frequency magnetron sputtering. After the properties are optimized by annealing, the heterojunctions exhibit significant rectification characteristics. The influence of annealing temperature on the electrical properties of the heterojunctions have been investigated. The optimal ideality factor of about 1.22 can be obtained with a rectification ratio of 1.05 x 105 after the heterojunctions annealing at 100 degrees C. This value is superior to most of the results reported in the literature. Meanwhile, the light-to-dark current ratio and the transmittance in the visible region of the heterojunction have also been studied. The light-to-dark current ratio is significant at 6.42 x 106. The average transmittance of the heterojunctions is 72.7%. These findings demonstrate the potential applications of CuI for optoelectronic devices and the promising prospects of p-CuI/n-ZnO heterojunction-based photodetectors and other optoelectronic devices.