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Impact of CdTe surface composition on doping and device performance in close Space sublimation deposited CdTe solar cells
Author(s) -
Major J. D.,
Proskuryakov Y. Y.,
Durose K.
Publication year - 2013
Publication title -
progress in photovoltaics: research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.286
H-Index - 131
eISSN - 1099-159X
pISSN - 1062-7995
DOI - 10.1002/pip.1196
Subject(s) - sublimation (psychology) , cadmium telluride photovoltaics , grain boundary , analytical chemistry (journal) , passivation , materials science , acceptor , doping , solar cell , getter , cadmium , inorganic chemistry , chemistry , optoelectronics , metallurgy , nanotechnology , layer (electronics) , microstructure , psychology , physics , chromatography , condensed matter physics , psychotherapist
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 <3% to 12% in controlled trials. Capacitance‐voltage analysis of such devices revealed an increase in the acceptor concentration from 3.76 × 10 13 cm −3 to 5.6 × 10 14 cm −3 , whereas thermal admittance spectroscopy revealed fewer deep states at energies >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.