Physical and Technological Foundations of the «Chloride» Treatment of Cadmium Telluride Layers for Thin-film Photoelectric Converters

Authors D.A. Kudii , М.G. Khrypunov , R.V. Zaitsev , A.L. Khrypunova

National Technical University «Kharkiv Polytechnic Institute», 2, Kyrpychov Str., 61002 Kharkiv, Ukraine

Issue Volume 10, Year 2018, Number 3
Dates Received 13 January 2018; published online 25 June 2018
Citation D.A. Kudii, М.G. Khrypunov, R.V. Zaitsev, A.L. Khrypunova, J. Nano- Electron. Phys. 10 No 3, 03007 (2018)
PACS Number(s) 68.55.Jk, 68.47.Fg
Keywords Photoelectric converter, Cadmium telluride films, Cadmium chloride, X-ray diffractometry (2) , Light current-voltage characteristics, Output parameters, Light diode characteristics.

The process of deposition of cadmium chloride films during the «chloride» treatment of cadmium telluride base layers for thin-film photoelectric converters (PEC) was studied. It is established that to ensure the reproducibility of the thickness and phase composition of cadmium chloride films, it is necessary to take into account the high hygroscopicity of this material. It is shown that the optimal growth rate of cadmium chloride films is 0.1 mm per minute. At high growth rates, cadmium chloride particulates are deposited on the surface of the CdTe layer base, which causes shunting of the PEC during the «chloride» treatment. It is determined that after the «chloride» treatment of CdTe layers, a coarse-grained structure is observed, which is predominantly oriented in the thermodynamic equilibrium direction [422]. In this case, the average grain size increases to 5 mm. It is shown that when performing a «chloride» treatment, the optimum purity of cadmium chloride layers is 98 %, which is due to the doping of CdTe with copper atoms. The disadvantage of copper with the use of more pure cadmium chloride reduces the efficiency of the PEC due to the increase in the series resistivity and the decrease in the photocurrent density. It has been experimentally determined that the optimum thickness of cadmium chloride during the «chloride» treatment and the efficiency of the PEC obtained at the same time depends on the substrate used. Thus, for the ITO/CdS/CdTe/Cu/Au PEC, the optimum thickness of cadmium chloride is 0.40 μm, the efficiency is 9.6 %, and for the NaCl/ITO/CdS/CdTe/Cu/Au PEC – 0.10 mm and 6.4 %, respectively.

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