Nanocrystalline ITO-SN2S^sub 3^ transparent thin films for photoconductive sensor applications

Nanocrystalline indium tin oxide (ITO) film containing 5 wt% Sn was prepared on glass substrate by the spray pyrolysis technique at a substrate temperature of 500 °C. In order to enhance the photosensitivity of ITO, thiourea (CS(NH2)^sub 2^ was added to the precursor to obtain the [S]/[In] proportion of 0.1, 0.2, 0.4 and 0.6. The X-ray diffraction patterns showed that beside the bixbyite structure of ITO, the characteristic peaks corresponding to SN2S^sub 3^ appeared in XRD profiles recorded for the films with [S]/[In] = 0.1 and 0.2. In addition, sulfur additive caused a considerable decline in crystallinity quality. The optical properties of the films were studied using transmittance measurements in the wavelength range 300-1,000 nm. As a result, ITO and ITO-SN2S^sub 3^ thin films were prepared with resistivity of 3.06-3.7 × 10^sup -4^ Ω cm and a transmittance of 88-91 % at the wavelength of 550 nm. Moreover, the electrical resistances of ITO and ITO-SN2S^sub 3^ films as a function of time were measured in darkness and under illumination of light in the visible range. The photoresistance results revealed that the ITO-SN2S^sub 3^ film with [S]/[In] = 0.2 was efficiently sensitive to visible light for photoconductive sensor applications, besides being high conductive and transparent.[PUBLICATION ABSTRACT]