Controlled Growth of Indium Oxide Nanowires for Gas Sensing Application.

BACKGROUND

The InO nanowires have attracted enormous attention for gas sensor application due to their advantageous features. However, the controlled synthesis of InO nanowires for gas sensors is vital and challenging because the gas sensing performance of the nanowires is strongly dependent on their characteristics.

METHODS

Here in this patent, we fabricated InO nanowires on SiO/Si substrate via a simple thermal vapor deposition method with the Au thin film as the catalyst. The growth temperatures were controlled to obtain desired nanowires of small size. The grown InO nanowires were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The ethanol gas sensing properties were tested under the dynamic flow of dry air and analytic gas. The synthesized InO nanowires have the potential for use in ethanol gas sensor application.

RESULTS

InO nanostructures grown at different temperatures ranging from 600 to 900oC have different morphologies. The sample grown at 600oC had a morphology of nanowire, with a diameter of approximately 80 nm and a length of few micrometers. Nanowires grown at 600°C were composed of oxygen (O) and indium (In) elements, with the atomic ratio of [O]/[In] = 3/5. The nanowire was a single phase cubic structure of InO crystal. The InO nanowire sensor showed typical n-type semiconducting sensing properties. The response decreased from 130 to 75 at 100 ppm when the working temperature decreased from 450°C to 350°C.

CONCLUSION

The nanowires grown at 600°C by the thermal vapor deposition method had the best morphology with a small diameter of about 80 nm and a length of few micrometers. The InO nanowires had a good ability to sense ethanol at varying concentrations in the range of 20 ppm to 100 ppm. The InO nanowires can be used as building blocks for future nanoscale gas sensors.