Ultra-sensitive UV sensors based on porous silicon carbide thin films on silicon substrate

Abstract

In this report, high-performance ultraviolet (UV) detectors were designed based on porous silicon carbide (SiC) thin films on silicon (Si) substrate. The results can broaden the applications of porous SiC structures in sensing applications. Here, n-type Si (100) was used as a substrate for epitaxial growth of SiC thin films. In order to fabricate porous SiC thin films, a two-electrode, photo-assisted electrochemical etching process was carried out using an integrated current source. The improvement in optical characteristics of porous SiC/Si was reported by tuning the anodization current density. It was illustrated that current density is an effective parameter for controlling the morphology of porous samples. The optical properties of samples were studied using photoluminescence (PL) and optical reflectometry. The results showed that by applying an optimized value of etching current density, the optical reflectivity is decreased which is due to the elevated specific surface area of porous samples that captures the incident light and reduces the reflection. Enhancement in porosity of optimized porous SiC/Si sample was illustrated by its elevated PL intensity. The UV sensing capability of fabricated metal-semiconductor-metal (MSM) detectors based on porous SiC/Si samples with different etching current densities was investigated. The device based on the optimized porous sample showed enhanced sensitivity (54.51) to UV illumination due to the elevated photogenerated current. Moreover, the ultrafast sensing behavior of this device indicates its improved optoelectrical performance in UV detection.