Effect of interfacial native oxide on the IV characteristics of ZnO/Si(111) heterojunction

Abstract

n-ZnO/p-Si(111) heterojunctions, with and without interfacial oxide layer, have been fabricated by growing Zn thin films on Si(111) substrate via DC Magnetron sputtering followed by oxidation in air at 800 °C. The specimen with and without interfacial oxide layer is referred to as ZnO/Si_RCA and ZnO/Si_HF respectively. Quality of the thin film has been studied using Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD). Temperature dependent surface (30 °C - 200 °C) and interfacial (30 °C - 150 ۠°C) current-voltage (T-IV) measurements of both specimens have been studied, under ambient conditions. Surface IV characteristics of ZnO/Si_HF shows lower current response compared to ZnO/Si_RCA. This has been attributed to diffusion of carriers across the junction. ZnO/Si_RCA shows a high ideality factor of 18.9 at 30 °C which decreases to 7.4 at 150 °C. ZnO/Si_HF shows a reduced ideality factor of 11.1 at 30 °C which further decreases to 6.6 at 150 °C.