Cupric Oxide thin films deposition for gas sensor application

Abstract

The present work deals with the deposition of CuO thin films by a simple and cheap technique such as Spray ultrasonic pyrolysis (SP). In the first, a set of CuO thin film was prepared using various deposition conditions in order to optimize the technique and prepare suitable films devoted to the photovoltaic and sensing applications. The studied deposition parameters were the substrate temperature, flow rate, salt nature and concentration. The structural analysis shows that the obtained films are polycrystalline, they exhibit a monoclinic structure. The preferential orientation is strongly related to the experimental parameters studies. From the optical and electrical characterization results, we inferred that the deposited films have suitable optoelectronic properties for the photovoltaic applications since they present a good absorption in the visible range. The fabricated CuO based sensor show a very high sensitivity equivalent to 90% at lower operation temperature equal to 50°C towards 300 ppm of methanol vapor. The sensing layer exhibits response and recovery times of 2,45 min and 2,02 min respectively with limit detection equal to 20 ppm. For ethanol sensing, the CuO based gas sensor show a sensitivity equal to 45% towards 300 ppm concentration of ethanol at operation temperature equal to 150°C. Response and recovery times are 2,98 min and 2,11 min respectively with limit detection at 25 ppm. The fabricated CuO based gas sensor show also a relative gas response equal to 9% at lower operation temperature above 60°C for CO2 pressure at 5hPa. The response and recovery times are ranged from 29 to 41 s and 30 to 35 s respectively occurring increases in sensitivity from 4.67 to 13.46 % when varying the CO2 pressure from 2 to 20 hPa. The obtained solar cells devices for CuO/ZnO and CuO/ZnS have low efficiencies equal to 5.2 x 10-4 and 7 x 10-4 %, respectively.