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Characterizing the effects of silver alloying in chalcopyrite CIGS with junction capacitance methods

Published online by Cambridge University Press:  31 January 2011

Peter Erslev
Affiliation:
[email protected], Materials Science Institute, Physics Department, Eugene, Oregon, United States
Gregory M. Hanket
Affiliation:
[email protected], Institute of Energy Conversion, University of Delaware, Newark, Delaware, United States
William N. Shafarman
Affiliation:
[email protected], Institute of Energy Conversion, University of Delaware, Newark, Delaware, United States
David J. Cohen
Affiliation:
[email protected], Materials Science Institute, Physics Department, Eugene, Oregon, United States
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Abstract

A variety of junction capacitance-based characterization methods were used to investigate alloys of Ag into Cu(In1-xGax)Se2 photovoltaic solar cells over a broad range of compositions. Alloys show encouraging trends of increasing VOC with increasing Ag content, opening the possibility of wide-gap cells for use in tandem device applications. Drive level capacitance profiling (DLCP) has shown very low free carrier concentrations for all Ag-alloyed devices, in some cases less than 1014 cm−3, which is roughly an order of magnitude lower than that of CIGS devices. Transient photocapacitance spectroscopy has revealed very steep Urbach edges, with energies between 10 meV and 20 meV, in the Ag-alloyed samples. This is in general lower than the Urbach edges measured for standard CIGS samples and suggests a significantly lower degree of structural disorder.

Type
Research Article
Copyright
Copyright © Materials Research Society 2009

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