Impact of CdTe surface composition on doping and device performance in close Space sublimation deposited CdTe solar cells

ABSTRACT Cool‐down after close‐space sublimation growth of cadmium telluride films has been shown to lead to the formation of a Cd‐rich surface that can block the subsequent in‐diffusion of cadmium chloride that is used in post‐growth doping of solar cell devices. Pre‐etching of the as‐grown surface...

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Bibliographic Details
Published in:Progress in photovoltaics 2013-06, Vol.21 (4), p.436-443
Main Authors: Major, J. D., Proskuryakov, Y. Y., Durose, K.
Format: Article
Language:English
Subjects:
admittance spectroscopy
Applied sciences
Cadmium
Cadmium tellurides
CdTe
Devices
Doping
Energy
Etching
Exact sciences and technology
Grain boundaries
Natural energy
Photovoltaic cells
Photovoltaic conversion
solar
Solar cells
Solar cells. Photoelectrochemical cells
Solar energy
thin film
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Summary:ABSTRACT Cool‐down after close‐space sublimation growth of cadmium telluride films has been shown to lead to the formation of a Cd‐rich surface that can block the subsequent in‐diffusion of cadmium chloride that is used in post‐growth doping of solar cell devices. Pre‐etching of the as‐grown surfaces using a nitric–phosphoric acid etch prior to doping leads to increase in chlorine and oxygen in‐diffusion, and an associated improvement in device efficiency from 0.4 eV for etched devices. Impedance analysis showed the improved cadmium chloride treatment—resulting from the additional etching step—removed the grain boundary component from the equivalent circuit, indicating a grain boundary passivation effect. Copyright © 2011 John Wiley & Sons, Ltd. The in‐diffusion of chlorine and oxygen species into CdTe layers is shown to be hindered by a Cd‐rich surface layer. By etching the surface prior to CdCl2 treatment, significant increases in device performance are achieved.
ISSN:1062-7995
1099-159X
DOI:10.1002/pip.1196