Characterization of gallium-doped CdS thin films grown by chemical bath deposition

    Authors

    H. Khallaf; G. Chai; O. Lupan; L. Chow; S. Park;A. Schulte

    Abstract

    Ga-doped CdS thin films, with different [Ga]/[Cd] ratios, were grown using chemical bath deposition. The effect of Ga-doping on optical properties and bandgap of CdS films is investigated. Resistivity, carrier density, and mobility of doped films were acquired using Hall effect measurements. Crystal structure as well as crystal quality and phase transition were determined using X-ray diffraction (XRD) and Micro-Raman spectroscopy. Film morphology was studied using scanning electron microscopy, while film chemistry and binding states were studied using X-ray photoelectron spectroscopy (XPS). A minimum bandgap of 2.26 eV was obtained at [Ga]/[Cd] ratio of 1.7 x 10(2). XRD studies showed Ga3+ ions entering the lattice substitutionally at low concentration, and interstitially at high concentration. Phase transition, due to annealing, as well as induced lattice defects, due to doping, were detected by Micro-Raman spectroscopy. The highest carrier density and lowest resistivity were obtained at [Ga]/[Cd] ratio of 3.4 x 10(2). XPS measurements detect an increase in sulfur deficiency in doped films. (C) 2008 Elsevier B. V. All rights reserved.

    Journal Title

    Applied Surface Science

    Volume

    255

    Issue/Number

    7

    Publication Date

    1-1-2009

    Document Type

    Article

    First Page

    4129

    Last Page

    4134

    WOS Identifier

    WOS:000262245500039

    ISSN

    0169-4332

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