title: CdCl2Treatment-Induced Enhanced Conductivity in CdTe Solar Cells Observed Using Conductive Atomic Force Microscopy.
abstract: The rear surfaces of CdTe photovoltaic devices without back contacts, grown by close-spaced sublimation (CSS), were analyzed using conductive atomic force microscopy (C-AFM). As-deposited and CdCl2-treated CdTe samples were compared to clarify the effect of the treatment on charge flow through grains and grain boundaries. The CdCl2-treated samples exhibit a more homogeneous and enhanced current flow across the grains as compared to the as-deposited samples. The grain boundaries show variable current. Under high bias, grain boundaries dominate current flow when the main junction is reverse biased and with the conducting current in reverse breakdown. Under the opposite bias conditions, where the contact of the conductive tip to the surface is reverse biased and under breakdown conditions, the current flow is uniform with little contrast between grains and grain boundaries. The results are interpreted as resulting from the improved crystallinity of the CdTe with reduced p-type doping along the grain boundaries.
authors.affiliation: Department of Materials Science and Engineering, University of Illinois , Urbana, Illinois 61801, United States.
authors.forename: Mohit
authors.identifier: http://orcid.org/0000-0003-2365-9820
authors.initials: M
authors.lastname: Tuteja
authors.affiliation: Department of Materials Science and Engineering, University of Illinois , Urbana, Illinois 61801, United States.
authors.forename: Antonio B
authors.initials: AB
authors.lastname: Mei
authors.affiliation: Department of Electrical Engineering, University of South Florida , Tampa, Florida 33620, United States.
authors.forename: Vasilios
authors.initials: V
authors.lastname: Palekis
authors.affiliation: Department of Materials Science and Engineering, University of Illinois , Urbana, Illinois 61801, United States.
authors.forename: Allen
authors.initials: A
authors.lastname: Hall
authors.affiliation: Frederick Seitz Materials Research Laboratory, University of Illinois , Urbana, Illinois 61801, United States.
authors.forename: Scott
authors.initials: S
authors.lastname: MacLaren
authors.affiliation: Department of Electrical Engineering, University of South Florida , Tampa, Florida 33620, United States.
authors.forename: Chris S
authors.initials: CS
authors.lastname: Ferekides
authors.affiliation: Department of Materials Science and Engineering, University of Illinois , Urbana, Illinois 61801, United States.
authors.forename: Angus A
authors.initials: AA
authors.lastname: Rockett