Fabrication of gas-sensing semiconductor oxide thin films by using a short-wavelength excimer laser

Semiconducting metal oxides are widely used in chemical, electronic devices and in gas sensing applications. Among the many different deposition techniques, ablating the target materials with a high power laser is one of the most effective techniques in fabricating high quality gassensitive thin films. In this work, we used a 193-nm-wavelength ArF excimer laser, the shortest wavelength used in the fabrication of semiconductor oxides, to deposit high quality transition-metaloxide thin films. We used X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, optical transmission spectroscopy, and conductivity measurements to characterize the films. The fabricated MoO 3 thin films were observed to show a good nanoplate structure in the orthorhombic α-MoO 3 phase. Depending on the deposition temperatures, MoO 3 showed significantly different surface structures. Good gas sensitivity of a MoO 3 thin-film-based sensor exposed to low concentrations ethanol vapor was found by using resistance measurements.