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Layered Surface Acoustic Wave (SAW) devices with an InO_x/SiN_u/36°YX LiTaO_3 structure were investigated for sensing low concentrations of hydrogen (H_2) and ozone (O_3) at different operating temperatures.The sensor consists of a 1μm thick silicon nitride (SiN_y) intermediate layer deposited by electron beam evaporation on a 36°Y-cut X-propagating piezoelectric lithium tantalate (LiTaO_3) substrate and a 100 nm thin indium oxide (InO_x) sensing layer deposited by R.F.magnetron sputtering.The device fabrication is described and the performance of the sensor is analyzed in terms of response magnitude as a function of operating temperature.Large frequency shifts of 360 kHz for 600μg/g of H_2 and 92 kHz for 40 ng/g O_3 were recorded.In addition,the surface morphology of the deposited films were investigated by Atomic Force Microscopy (AFM) and the chemical composition by X-Ray Photoelectron Spectroscopy (XPS) to correlate gas-sensing behavior to structural characteristics of the thin film.
Layered Surface Acoustic Wave (SAW) devices with an InO_x / SiN_u / 36 ° YX LiTaO_3 structure were investigated for sensing low concentrations of hydrogen (H_2) and ozone (O_3) at different operating temperatures.The sensor consists of a 1μm thick silicon nitride SiN_y) intermediate layer deposited by electron beam evaporation on a 36 ° Y-cut X-propagating piezoelectric lithium tantalate (LiTaO_3) substrate and a 100 nm thin indium oxide (InO_x) sensing layer deposited by RFmagnetron sputtering.The device fabrication is described and the performance of the sensor is analyzed in terms of response magnitude as a function of operating temperature. Larger frequency shifts of 360 kHz for 600 μg / g of H_2 and 92 kHz for 40 ng / g O_3 were recorded. In addition, the surface morphology of the deposited films were investigated by Atomic Force Microscopy (AFM) and the chemical composition by X-Ray Photoelectron Spectroscopy (XPS) to correlate gas-sensing behavior to structural characteristics of the thin film.