Abstract
We report on the growth, grain enhancement, doping, and electron mobility of cadmium selenide (CdSe) thin films deposited using the thermal evaporation method. The optical measurement shows CdSe is a direct bandgap material with an optical bandgap (Egap) of 1.72 eV. CdSe thin films were deposited on fluorine doped tin oxide glass substrates with different thicknesses, and grain size and mobility were measured on the films. CdCl2 was deposited on the films, and the films were subjected to high temperature treatment for several hours. It was found that both grain sizes increased significantly after CdCl2 treatment. The mobility of electrons was measured using the space charge limited current technique, and it was found that the mobility increased significantly after CdCl2 treatment. It was discovered that postdeposition selenization further improved the electrical properties of CdSe thin films by increasing the electron mobility-lifetime product and the photo/dark conductivity ratio. CdSe films after postselenization also showed significantly lower values for midgap states and Urbach energies for valence band tail states.
Highlights
cadmium selenide (CdSe) is a II-VI group semiconductor chalcogenide which is potentially an attractive material for photovoltaic energy conversion since its bandgap is around the value (∼1.7 eV) needed for use in a tandem junction solar cell with silicon acting as the bottom cell.1–3 Theoretical calculations indicate that it is possible to attain a thermodynamic efficiency of ∼45% in a tandem cell of CdSe and cSi.4 CdSe is a binary compound; it is easier to achieve stoichiometry than in a ternary or quaternary material
We report on the growth, grain enhancement, doping, and electron mobility of cadmium selenide (CdSe) thin films deposited using the thermal evaporation method
CdSe is a II-VI group semiconductor chalcogenide which is potentially an attractive material for photovoltaic energy conversion since its bandgap is around the value (∼1.7 eV) needed for use in a tandem junction solar cell with silicon acting as the bottom cell
Summary
CdSe is a II-VI group semiconductor chalcogenide which is potentially an attractive material for photovoltaic energy conversion since its bandgap is around the value (∼1.7 eV) needed for use in a tandem junction solar cell with silicon acting as the bottom cell. Theoretical calculations indicate that it is possible to attain a thermodynamic efficiency of ∼45% in a tandem cell of CdSe and cSi. CdSe is a binary compound; it is easier to achieve stoichiometry than in a ternary or quaternary material. CdSe is a II-VI group semiconductor chalcogenide which is potentially an attractive material for photovoltaic energy conversion since its bandgap is around the value (∼1.7 eV) needed for use in a tandem junction solar cell with silicon acting as the bottom cell.. CdSe is not water soluble and does not thermally decompose, unlike Pb-halide perovskites.. CdSe is not water soluble and does not thermally decompose, unlike Pb-halide perovskites.5 It is a direct bandgap semiconductor, and, only a thin film is needed to absorb photons. We report on deposition of CdSe thin films using physical vapor deposition at a high growth temperature of ∼400 ○C with different thicknesses in the range of 0.5 μm–3 μm. We show that postdeposition treatments using CdCl2 increase the grain size and mobility of CdSe significantly. Further high temperature selenization treatment under a Se flux serves to further increase the mobility
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