Highly Performing MSM Type Ag/n-titanium Dioxide Nanotubes/p-Si Heterojunction Based Ultraviolet-A Photodetectors

Recently, heterojunction-based ultraviolet (UV) photodetectors (PDs) have found a wide range of applications in day-to-day life. The fabrication of these UV PD devices using high-k TiO₂ nanostructures i.e. nanotubes (NTs) at low temperature processing steps in association with cost-effective deposition methods is crucial. In this work, Ag/n-TiO₂NTs/p-Si heterojunction-based MSM UV PD devices were fabricated using hydrothermal, spin coating and e-beam evaporation methods. The structural, chemical, optical, morphological and elemental composition characteristics of the formed TiO₂NTs/p-Si stacks were explored by XRD/Raman, XPS, UV–Vis, FESEM and EDS techniques, respectively. XRD and FESEM analysis revealed the formation of anatase phase of TiO₂NTs with an average diameter of ~ 16.1 nm and length of ~ 50.9 nm. XPS investigation revealed two intense core level BE peaks of Ti2p_3/2 and Ti2p_1/2. The photodetection parameters of the fabricated MSM UV PD device were systematically checked in dark and UV-A light (320–400 nm) illumination. At 3 V, the fabricated Ag/n-TiO₂NTs/p-Si device presented superior photosensing properties with a responsivity of 570 mA/W, EQE of 189% and rise/decay times of 120 ms/95 ms. Further, the superior structural and photosensing parameters attained from the fabricated MSM UV PD device may expand its scope to serve as a future cost-effective alternative to other wide bandgap semiconductor (GaN, SiC and ZnO) based heterojunction PD devices.