Fabrication of High Sensitive UV Photodetector Based on n-ZnO Nanowire/n-Porous-Si Heterojunction

Abstract

In this paper, we have reported the high sensitive UV detector using ZnO nanowires prepared on porous silicon (PS). The aligned naturally doped n-type zinc oxide (ZnO) nanowires were grown on both PS and n-Si(100) substrates to produce isotype heterojunctions using hydrothermal method. The length of the nanowires ranges 3–4[Formula: see text][Formula: see text]m and the diameter 150–200[Formula: see text]nm. Grown ZnO nanowires on PS substrate has lower reflectivity value compared with Si substrate. The electrical behavior of such devices has been examined at different intensities of UV radiation. The current–voltage curve of the isotype heterojunction shows rectifying behavior in a dark environment. Under UV light, the current was increased by using PS instead of n-Si under reverse bias. The I–V characteristics of the device show a significant rise in the current for low intensity of UV radiation evidencing the high sensitivity of the reported structure. The sensitivity for such devices is obtained, [Formula: see text] and [Formula: see text] at UV radiation of 1.5[Formula: see text]mW/cm2 intensity at bias voltage of −0.75 V for three proposed structures. The samples have been analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) to investigate their structures and geometries.