Investigation of aluminium and indium in situ doping of chemical bath deposited CdS thin films

    Authors

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

    Comments

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    Abbreviated Journal Title

    J. Phys. D-Appl. Phys.

    Keywords

    CADMIUM-SULFIDE FILMS; OPTICAL-PROPERTIES; CUBIC CDS; RAMAN; PHOTOLUMINESCENCE; SEMICONDUCTOR; SPECTROSCOPY; PARAMETERS; CRYSTALS; WURTZITE; Physics, Applied

    Abstract

    Aluminum and indium in situ doping of CdS using chemical bath deposition (CBD) is investigated. The effects of Al and In-doping on optical properties as well as on electrical properties, crystal structure, chemistry and morphology of CdS films are studied. Al doping of CdS using CBD is shown to be successful where a resistivity as low as 4.6 x 10(-2) Omega cm and a carrier density as high as 1.1 x 10(19) cm(-3) were achieved. The bandgap of Al-doped films decreases to a minimum of 2.26 eV, then slightly increases and finally saturates at 2.30 eV as the [Al]/[Cd] ratio in solution increases from 0.018 to 0.18. X-ray diffraction studies showed Al3+ ions entering the lattice substitutionally at low concentration and interstitially at high concentration. Phase transition, due to annealing, and induced lattice damage, due to doping, were detected by micro-Raman spectroscopy. Film stoichiometry was found to be sensitive to Al concentration, while film morphology was unaffected by Al doping. Indium doping using CBD, however, was found to be highly unlikely due to the low solubility of indium sulfide. Instead, the formation of InS/In2S3 dominated the deposition process over CdS.

    Journal Title

    Journal of Physics D-Applied Physics

    Volume

    41

    Issue/Number

    18

    Publication Date

    1-1-2008

    Document Type

    Article

    Language

    English

    First Page

    10

    WOS Identifier

    WOS:000258985500026

    ISSN

    0022-3727

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