Preparation and room temperature NO2-sensing performances of porous silicon/V2O5 nanorods.

In this paper, porous silicon/V2O5 nanorod composites are prepared by a heating process of as-sputtered V film on porous silicon (PS) at 600 °C for different times (15, 30, and 45 min) in air. The morphologies and crystal structures of the samples are investigated by field emission scanning electron microscope (FESEM), x-ray diffractometer (XRD), x-ray photoelectron spectroscopy (XPS), and Raman spectrum (RS). An improved understanding of the growth process of V2O5 nanorods on PS is presented. The gas sensing properties of samples are measured for NO2 gas of 0.25 ppm∼3 ppm at 25 °C. We investigate the effects of the annealing time on the NO2-sensing performances of the samples. The sample obtained at 600 °C for 30 min exhibits a very strong response and fast response-recovery rate to ppm level NO2, indicating a p-type semiconducting behavior. The XPS analysis reveals that the heating process for 30 min produces the biggest number of oxygen vacancies in the nanorods, which is highly beneficial to gas sensing. The significant NO2 sensing performance of the sample obtained at 600 °C for 30 min probably is due to the strong amplification effect of the heterojunction between PS and V2O5 and a large number of oxygen vacancies in the nanorods. [ABSTRACT FROM AUTHOR]