Peter Korir - Academia.edu (original) (raw)
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National Institute of Technology, Calicut
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Papers by Peter Korir
Physica B: Condensed Matter, 2017
In this work two step growth process was used to prepare Cu(In, Ga)Se 2 thin film for solar cell ... more In this work two step growth process was used to prepare Cu(In, Ga)Se 2 thin film for solar cell applications. The first step involves deposition of Cu-In-Ga precursor films followed by the selenization process under vacuum using elemental selenium vapor to form Cu(In,Ga)Se 2 film. The growth process was done at a fixed temperature of 515°C for 45, 60 and 90 min to control film thickness and gallium incorporation into the absorber layer film. The X-ray diffraction (XRD) pattern confirms single-phase Cu(In,Ga)Se 2 film for all the three samples and no secondary phases were observed. A shift in the diffraction peaks to higher 2θ (2 theta) values is observed for the thin films compared to that of pure CuInSe 2. The surface morphology of the resulting film grown for 60 min was characterized by the presence of uniform large grain size particles, which are typical for device quality material. Photoluminescence spectra show the shifting of emission peaks to higher energies for longer duration of selenization attributed to the incorporation of more gallium into the CuInSe 2 crystal structure. Electron probe microanalysis (EPMA) revealed a uniform distribution of the elements through the surface of the film. The elemental ratio of Cu/(In + Ga) and Se/Cu + In + Ga strongly depends on the selenization time. The Cu/In + Ga ratio for the 60 min film is 0.88 which is in the range of the values (0.75-0.98) for best solar cell device performances.
Journal of Applied Physics, 1993
Zinc selenide (ZnSe) thin films were deposited on to chemically and ultrasonically cleaned glass ... more Zinc selenide (ZnSe) thin films were deposited on to chemically and ultrasonically cleaned glass substrates at different substrate temperatures from room temperature to 200C keeping the thickness fixed at 300 nm by using thermal evaporation method in vacuum. The structural properties of the films were ascertained by X-ray diffraction (XRD) method utilizing a diffractometer. The optical properties were measured in the photon wavelength ranging between 300 and 2500 nm by using a UV-VIS-NIR spectrophotometer. The XRD patterns reveal that the films were polycrystalline in nature exhibiting f.c.c zincblende structure with average lattice parameter, a = 5.6873Å. The grain size, strain and dislocation densities of the films have been calculated. The optical transmittance and reflectance were utilized to compute the absorption coefficient, band gap energy and refractive index of the films. The band gap energy of the films was extracted from the absorption spectra. The direct band gap energy of the films slightly increases with substrate temperature.
Physica B: Condensed Matter, 2017
In this work two step growth process was used to prepare Cu(In, Ga)Se 2 thin film for solar cell ... more In this work two step growth process was used to prepare Cu(In, Ga)Se 2 thin film for solar cell applications. The first step involves deposition of Cu-In-Ga precursor films followed by the selenization process under vacuum using elemental selenium vapor to form Cu(In,Ga)Se 2 film. The growth process was done at a fixed temperature of 515°C for 45, 60 and 90 min to control film thickness and gallium incorporation into the absorber layer film. The X-ray diffraction (XRD) pattern confirms single-phase Cu(In,Ga)Se 2 film for all the three samples and no secondary phases were observed. A shift in the diffraction peaks to higher 2θ (2 theta) values is observed for the thin films compared to that of pure CuInSe 2. The surface morphology of the resulting film grown for 60 min was characterized by the presence of uniform large grain size particles, which are typical for device quality material. Photoluminescence spectra show the shifting of emission peaks to higher energies for longer duration of selenization attributed to the incorporation of more gallium into the CuInSe 2 crystal structure. Electron probe microanalysis (EPMA) revealed a uniform distribution of the elements through the surface of the film. The elemental ratio of Cu/(In + Ga) and Se/Cu + In + Ga strongly depends on the selenization time. The Cu/In + Ga ratio for the 60 min film is 0.88 which is in the range of the values (0.75-0.98) for best solar cell device performances.
Journal of Applied Physics, 1993
Zinc selenide (ZnSe) thin films were deposited on to chemically and ultrasonically cleaned glass ... more Zinc selenide (ZnSe) thin films were deposited on to chemically and ultrasonically cleaned glass substrates at different substrate temperatures from room temperature to 200C keeping the thickness fixed at 300 nm by using thermal evaporation method in vacuum. The structural properties of the films were ascertained by X-ray diffraction (XRD) method utilizing a diffractometer. The optical properties were measured in the photon wavelength ranging between 300 and 2500 nm by using a UV-VIS-NIR spectrophotometer. The XRD patterns reveal that the films were polycrystalline in nature exhibiting f.c.c zincblende structure with average lattice parameter, a = 5.6873Å. The grain size, strain and dislocation densities of the films have been calculated. The optical transmittance and reflectance were utilized to compute the absorption coefficient, band gap energy and refractive index of the films. The band gap energy of the films was extracted from the absorption spectra. The direct band gap energy of the films slightly increases with substrate temperature.