Effect of precursor concentration on the performance of UV photodetector using TiO2/reduced graphene oxide (rGO) nanocomposite

This study evaluates the photodetection performance of metal-semiconductor-metal (MSM) ultraviolet photo-detector based on TiO2 and TiO2/rGO films deposited on glass substrates. TiO2/rGO thin films with different concentrations of GO (1, 5, 7 and 10 wt%) were deposited on the glass substrates using spray pyrolysis technique (SPT). The TiO2 and TiO2/rGO samples were characterized using Raman spectroscopy, Field Emission Scanning Electron Microscope (FESEM), X-ray diffraction (XRD), and UV spectroscopy (UV) to determine the effect of rGO concentration on the morphology, crystal structure and optical properties of the TiO2/rGO thin films. The successful interface between TiO2 and rGO was confirmed by the broadening characteristic of the XRD peak for anatase TiO2, increasing D and G band intensity ratios (I-D/I-G) of Raman spectra from 1.05 to 1.9, and decreasing intensity of UV-Vis transmittance spectra as the rGO concentration is increased from 1 to 10 wt%. The decline in the energy bandgap of the thin films from 3.60 to 3.04 eV with the increase in rGO concentration proves the effect of rGO concentration on conductivity. Al metal contacts were sputtered on the thin film samples using RF sputtering to fabricate the MSM photodetector. The photoresponse (R), sensitivity (S%), photodetector gain (G), and recovery times of the photodetector under 375 nm UV illumination (0.37 mW/cm(2)) and bias voltage of 3 V show that TiO2/rGO thin film prepared via SPT is a promising material for a high quality MSM photodetectors, and confirms the effect of GO concentration on the photodetection performance.