• L P PUROHIT

      Articles written in Pramana – Journal of Physics

    • Highly transparent and conducting Al-doped ZnO as a promising material for optoelectronic applications

      RISHABH RAJ HIMANSHU GUPTA L P PUROHIT

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      Al-doped ZnO (AZO) thin films have been deposited onto the glass substrate via sol–gel spin coating method with different Al concentrations (0, 2, 4, 6, 8, 10 at.%). The growth orientation and crystalline structure were investigated by studying the X-ray diffraction (XRD) pattern. The XRD results reveal that the thin films show wurtzite phase with preferential orientation along the $c$-axis (002) plane for lower concentration of Al. The diffraction peak gets weaker corresponding to plane (002) and the diffraction peaks of planes (101) and (100) become stronger with higher concentration of Al content. The field emission scanning electron microscopy (FESEM) images confirm that thin films show wrinkle-type structure with a few minor cracks. The transmittance spectra of thin films were recorded by UV–Vis spectrophotometer in the wavelength range 350–800 nm. The optical transmittance of thin films was found to be above 85%. The band-gap energy of AZO films varies from 3.16 eV to 3.27 eV with increasing concentration of Al. The better conductivity and high optical transparency of AZO films make them a more promising alternative to indium-doped tin oxide (ITO) for optoelectronic applications.

    • Effect of Li doping on passivation of trap states and improvement in charge transport in TiO$_2$ thin films

      MOHINI PANDAY GAURAV K UPADHYAY L P PUROHIT

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      In the framework of this study, pure and Li-doped TiO$_2$ (0.5, 1.5, 2.5 at.%) thin film samples were synthesised via sol–gel spin coating method. The structural, morphological and optical properties were examined by using X-ray diffraction, scanning electron microscopy (SEM) and UV–Vis spectroscopy respectively. XRD pattern reveals the polycrystalline nature of Li-doped TiO$_2$ thin films with anatase crystal phase. The average crystallite sizes were found to be in the range of 19–23 nm. The energy-dispersive X-ray spectroscopy (EDS) demonstrates the oxidation states of Ti, O and Li in the deposited thin films. The optical band gap of TiO$_2$ thin films was varied from 3.15 to 3.26 eV on increasing Li doping. For the study of light emission properties of Li-doped TiO$_2$ thin films, the PL spectra were recorded in the wavelength range of 350–700 nm. The doping of Li on TiO$_2$ films show improved charge transport properties which can be used in optoelectronics and energy storage devices.

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