Optimization of UVB photodiode based on ZnO nanorod arrays grown via the hydrothermal process

Abstract

In this work, n-Type ZnO nanorods (NRs) were grown on a p-type Si (100) substrate using the hydrothermal technique. These p-n heterojunctions were made to fabricate ZnO-based ultraviolet (UV) photodiodes (PDs). To study the effect of solution volume -in the hydrothermal process-on the structural properties of the ZnO NRs arrays, three samples were prepared with different conditions. SEM characterization shows the well-aligned ZnO NRs arrays grown on all three substrates. X-ray diffraction characterization indicates the crystalline structure of all samples with a preferred orientation of c-plane (002). XRD results show the ZnO grain size enlargement concerning solution volume. To analyze the electric characterization of the samples, the current-voltage (I–V) analysis was performed under dark and illuminated conditions. The I–V measurement indicates that the increase of growth solution volume is leading to increasing in the responsivity of ZnO-based PDs. Additionally, the PL and UV–Vis characterizations exhibit that the optical properties of samples were also affected and therefore could be controlled and optimized by growth conditions.