Browsing by Author "Majula, Lusato"

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    Investigation of kesterite materials - CZTS thin films prepared by spin coating technique for photovoltaic applications
    (Unversity of Dar es Salaam, 2014) Majula, Lusato
    Copper zinc tin sulphide, Cu2ZnSnS4 (CZTS) films have been broadly studied in recent years due to their advantages of low cost, high absorption coefficient ( ), appropriate band gap (~1.5 eV) and nontoxicity. In this work, CZTS films were prepared by spin coating on soda lime glass (SLG) substrate at room temperature using sol-gel precursor solutions which were categories as stoichiometric or nonstoichiometric and confirmed with SEM data. To remove all organic remnants and changing from insulator to semiconductor phase, the CZTS samples were annealed under N2 atmosphere in RTP furnace at temperature of 500 oC for ten minutes. After annealing, the films exhibited typical semiconductor properties for both compositions. Electrical properties as measured by Ecopia Hall Effect measurement system showed p-type semiconductor properties for both compositions. Carrier concentration was in the order of 1017-1019 cm-3, mobility was in the range of 0.30-7.03 . Resistivity values were in the order of . Optical properties were investigated using Hitachi U-2000 spectrophotometer in the 300 nm to 1100 nm wavelength range. The optical absorption coefficient for all CZTS films was determined to be above in visible region. The refractive indices and extinction coefficients were determined to be in the range of 6.6-7.5 and 0.03-0.22 respectively. The band gap was in the range of ~1.4-1.6 eV in good agreement with reported values for stoichiometric CZTS samples. The XRD results had diffraction peaks showing that, all annealed CZTS films had kesterite structure