Departments of Physics

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    EFFECT OF DEPOSITION TIME ON STRUCTURAL AND OPTICAL PROPERTIES OF CdS THIN FILM PREPARED BY CHEMICAL BATH DEPOSITION METHOD IN ALKALINE MEDIUM
    (HAWASSA UNIVERSITY, 2024-06) ABERASH BEKENA
    Cadmium Sulfide thin films were prepared by chemical bath deposition (CBD) technique at bath temperature of 800C for various deposition time. The bath solution was a mixture of cadmium chloride and thiourea as source of Cd2+ and S2- respectively and ammonia hydroxide was used as complexing agent in basic medium. After deposition the film were annealed at temperature of 3000C for 90min. The effect of deposition time on the structural and optical properties of CdS thin film were investigated by XRD, FT-IR and Uv-Vis spectroscopy characterization technique. The XRD analysis revealed CdS thin film were cubic (Hawleyite) structure. The diffracted peaks are indexed (111),(200), (220) and (311) planes and with preferred orientation along the (111) plane. Estimated crystallite size and optical band gap was found in range of 11.7nm to 16.12nm and 1.8ev to 2.06ev respectively for deposition time 30min to 60min in 10min interval. The functional group of CdS thin films were proposed based on FTIR result obtained. The absorbance generally decreased with increase in wavelength and has relatively low values in the infrared region of the spectrum. A strong absorption was observed at wavelength range of 400 nm to 600 nm.
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    STUDIES OF STRUCTURAL AND OPTICAL PROPERTIES OF LEAD SULFIDE THIN FILM AT DIFFERENT DEPOSITION TIME PREPARED BY CBD TECHINIQUE
    (HAWASSA UNIVERSITY, 2024-09) YIRGALEM FIKIRE ALEKER
    In this study, PbS thin films were deposited on glass substrates using the chemical bath deposition (CBD) technique. Lead acetate, thiourea, and sodium hydroxide were used as precursors for the Pb²⁺, S²⁻ source, and complexing agent, respectively. The deposition was carried out at a bath temperature of 80°C for varying durations of 20, 25, 30, 35, and 40 minutes. Following deposition, the films were annealed at 200°C for 90 minutes. The structural and optical properties of the films were characterized using X-ray diffraction (XRD) and UV-Visible spectroscopy. XRD analysis revealed that the as-deposited PbS films exhibited a nanocrystalline cubic (galena) structure with a face-centered cubic lattice, showing diffraction peaks corresponding to the (111), (200), (220), (222), (311), (400), (420), (331), and (422) planes, with a preferred orientation along the (200) plane. The crystallite size was estimated to increase from 33.27 nm to 37.50 nm as the deposition time increased. Additionally, both dislocation density and lattice strain decreased with increasing deposition time. Optical absorption measurements revealed strong absorption in the wavelength range of 500 nm to 750 nm. The optical band gap was reduced from 1.62 eV to 1.51 eV as the deposition time increased from 20 to 40 minutes in 5-minute intervals
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    THE EFFECT OF DEPOSITION TEMPRATURE ON THE CADMIUM DOPED COPPER OXIDE THIN FILMS DEPOSITED BY CHEMICAL BATH DEPOSITION METHOD
    (HAWASSA UNIVERSITY, 2024-11) SIMACHEW SHITAHUN
    The cadmium doped copper oxide thin films were deposited on the glass substrate for 30minutes by using chemical bath deposition. The bath contained the solution of cadmium chloride and copper acetate as a source of cadmium and copper ion respectively. Hydrazine and ammonia used as complexing agent at deposited temperature of 40ᵒC, 60ᵒC, 70ᵒC and 80ᵒC. The films were characteri zed using XRD and UV- VIS characterization techniques. According to X-ray diffraction analysis the prepared thin films revealed that monoclinic CuO and cubic Cu2O phases coexist in all samples. Th ere also was very weak peak of cubic face centered CdO only at lower deposition temperature 400C; however it was inhibited at deposition temperature 600C, 700C and 800C. The crystallinity of Cu2O and CuO phases were increased as deposition temperature increased except a slight decreased from 600C to 700C for Cu2O and from 70°C to 80°C for CuO. However, dislocation and lattice strain decr eased with increasing temperature, except a slight increased from 600C to 700C for Cu2O and from 7 0°C to 80°C for CuO. The optical study of the films showed that absorbance was higher at shortest wave length.The band gaps of the films were decreased from 1.95 eV to 1.90 eV for deposition temp erature increased from 400C - 800C