Study on the carrier transmission and luminescence characteristics of n-ZnO/p-Si heterojunction device by magnetron sputtering

In this study, Zinc oxide film was prepared on a sapphire substrate and a n-ZnO/p-Si heterojunction was fabricated following the optimum preparation parameters obtained in the previous stage by radio frequency (RF) magnetron sputtering. The results showed that the diffraction peaks have a preferred crystal orientation of (002) along the c-axis, the surface of the sample shown widely distributed “pill-like” grains with an overall uniform and dense appearance and a large average grain size (70.13 nm) at 1.3 Pa. The diode demonstrated excellent I–V characteristics and the turn-on voltage showed a decreasing trend with increasing of operating temperature. The device showed a large rectification ratio of about 352.2 when the applied voltage was ±2 V and the series resistance of the diode was determined to be 0.1 Ω. It manifested an impressively low leakage current of 1.37 × 10⁻¹⁰ A. Finally, the device was examined using an electroluminescence (EL) system, which showed visible light emission from the deep level of ZnO. It could be seen that the EL spectrum was fitted by four peaks, which were located in blue (470 nm), yellow-green (575 nm) and red (721 nm, 752 nm).