Synthesis of Psi/CuO/Cu2o Heterostructure for NH3 Vapor Detection at Room Temperature

Abstract

In this paper, we demonstrate the use of the heterostructure porous silicon PSi-n/CuO-p/Cu2O-n as an alternative structure for an efficient gas sensor for NH3 sensing. The porous silicon PSi was prepared using an electrochemical method and utilized as a substrate. Then, CuO homogeneous thin films were synthesized by thermal evaporation/oxidation on the pre-prepared PSi substrate, on which a uniform layer of Cu2O is deposited by electrodeposition method. The structural, morphological and optical characterizations of the obtained CuO and Cu2O films were carried out by XRD, SEM, FTIR, UV spectroscopy and contact angle measurements. Likewise, the electrical properties of CuO-p/Cu2O-n thin films, deposited on PSi-n, were studied by current-voltage (I-V) measurements at room temperature, within the sandwich (semiconductor/oxide/oxide) configuration. The NH3 gas sensing characteristics: response/recovery time, sensitivity and repeatability, were evaluated and tested at different gas concentrations at room temperature, allowing the determination of the different parameters of the heterojunction PSi/CuO/Cu2O.These results indicated that the PSi/CuO/Cu2O structure is a promising candidate for reliable high-performance NH3 gas sensors at room temperature, with a very high sensitivity to NH3 (80%) and with an extremely fast response time of the order of 1 second. These sensing performances enhancements at room temperature are due to the high surface area to volume ratio of PSi and the use of PSi/CuO/Cu2O heterostructure. The prospective sensing mechanism of the presented sensor has been discussed.