Fabrication and Characterization of Gas Sensors from ZnS/Porous Silicon Heterojunctions

Abstract

ZnS-PSi heterojunction based gas sensor was fabricated in this study. ZnS thin film as the active materials over PSi substrate was synthesized by spray pyrolysis method. The effected of different concentration of ZnS (0.1M , 0.3 M and 0.5 M) on the characterization of the sensor have been investigated. The XRD results show that the ZnS has a hexagonal structure. SEM images were revealed that the ZnS as a circular grains with different sizes is synthesized over the PSi substrate. The electrical properties of the prepared sensor were proved that the sensitivity of the sensor is improved by increasing the concentration the ZnS. Furthermore, the ZnS-PSi heterojunction based gas sensor display high sensitivity and fast response and recovery times. The maximum sensitivity is found to be 5.11 when the ZnS concentration is 0.5 M compared to the sensitivity of 3.14 when the ZnS concentration is 0.1M. The ZnS-PSi heterojunction based gas sensor may be used for UV-light photo-detectors due to a valuable properties such as high sensitivity and fast response.