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Fundamental Investigations of CdTe Deposited by MBE for Applications in Thin-Film Solar Photovoltaics

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posted on 20.06.2014, 00:00 authored by Eric Colegrove
Model CdTe systems –both single-crystalline (sx) and poly-crystalline (px) –are investigated experimentally as a means to understand the role of competing material properties and processing steps in improving the performance of standard thin-film solar cells. Previous device optimization work is reviewed explaining the close space sublimation growth technique and ongoing analysis using scanning transmission electron microscopy. This is followed by motivation for molecular beam epitaxy (MBE) growth studies of CdTe and the results of fundamental material investigations. The results show that (a) the minority carrier lifetimes in hetero-epitaxial layers is limited by surface recombination, (b) source selection and anneals can be tuned to achieve p-type carrier density of 6x1015 cm-3, and (c) counter-intuitively, the increase in p-density is associated with increased mobility in lower crystal quality samples, suggesting the role of anneal. Finally, controlled and re-growth of px-CdTe by MBE studies are discussed with results indicating that shorter lifetimes are directly correlated with the increased surface/interface density.

History

Advisor

Sivananthan, Sivalingam

Department

Physics

Degree Grantor

University of Illinois at Chicago

Degree Level

Doctoral

Committee Member

Klie, Robert Grein, Christoph Kodama, Richard Dhere, Ramesh Gessert, Timothy

Submitted date

2014-05

Language

en

Issue date

20/06/2014