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Recrystallization and sulfur diffusion in CdCl 2 ‐treated CdTe/CdS thin films
Author(s) -
McCandless B. E.,
Moulton L. V.,
Birkmire R. W.
Publication year - 1997
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/(sici)1099-159x(199707/08)5:4<249::aid-pip178>3.0.co;2-s
Subject(s) - cadmium telluride photovoltaics , recrystallization (geology) , thin film , materials science , scanning electron microscope , analytical chemistry (journal) , transmission electron microscopy , grain boundary , chemistry , microstructure , optoelectronics , nanotechnology , metallurgy , composite material , paleontology , chromatography , biology
The role of CdCl 2 in prompting recrystallization, grain growth and interdiffusion between CdS and CdTe layers in physical vapor‐deposited CdS/CdTe thin‐film solar cells is presented. Several CdTe/CdS thin‐film samples with different CdTe film thicknesses were treated in air at 415°C for different times with and without a surface coating of CdCl 2 . The samples were characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive x‐ray spectroscopy, x‐ray diffractometry and optical absorption. The results show that CdCl 2 treatment enhances the recrystallization and diffusion processes, leading to a compositional variation within the CdTe layer due to diffusion of sulfur from the CdS. The highest sulfur concentrations observed after 30 min treatments with CdCl 2 at 415°C are near the solubility limit for sulfur in CdTe. The compositional distributions indicated by x‐ray diffraction measurements of samples with different CdTe thickness show that the S‐rich CdTe 1−x S x region lies near the CdTe/CdS interface. A multiple‐step mixing process must be inferred to account for the diffraction profiles obtained. © 1997 John Wiley & Sons, Ltd.