Correlation between Microstructure of Copper Oxide Thin Films and its Gas Sensing Performance at Room Temperature

Radio-frequency magnetron sputtering using a Cu target was used to deposit cuprous oxide and cupric oxide thin films on silicon wafer. The substrate bias voltage and the O2 flow ratio were varied during the deposition. The deposited thin films were characterized using scanning electron microscope. We found that the spherical and pyramid shapes structure of copper oxide thin films were deposited at critical O2 flow ratio between 7 and 14%. The influence of substrate bias voltage was small and negligible. The deposited thin films were used for sensing characterization using ethanol vapor. Experimental results reveal that the pyramid shape of copper oxide thin film contribute to high respond rate when exposed to ethanol vapor. The respond and recovery rates which were measured at room temperature were very fast. This work had successfully demonstrated the formation of optimized copper oxide thin films and their usage for gas sensing application.