Spatially Resolved Cathodoluminescence of CdTe Thin Films and Solar Cells

Conference · Thu May 01 00:00:00 EDT 2003

OSTI ID:15004264

Romero, M J; Metzger, W; Gessert, T A; Albin, D S; Al-Jassim, M M

We have investigated the spatial distribution of different transitions identified in the emission spectra of CdTe thin films and solar cells by cathodoluminescence spectroscopic imaging (CLSI). Prior to back-contact deposition, the spectra are dominated by excitons (X) and donor-to-acceptor (DAP) transitions. After contacting, Cu acceptor states are found in addition to the X and DAP recombination processes. A very systematic behavior found in CdTe is that DAP transitions occur preferentially at grain boundaries (GBs). The distribution of these states responsible for the passivation of GBs is not affected by further processing, although additional levels participate in the recombination process. We believe that this stability is one of the reasons for the success of thin-film CdTe solar cells. Estimates of the densities of different donors and acceptors participating in the recombination process are possible from the analysis of the evolution of the emission spectra with the excitation level. It is found that the back contact suppresses some intrinsic acceptors (associated with the A center) near the back-contact interface and, therefore, Cu acceptor states should be responsible for the p-typeness of the back surface more than a reduction of compensation. CLSI measurements are shown to be helpful in understanding the physics of back-contact formation.

• Research Organization: National Renewable Energy Lab. (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC36-99-GO10337
• OSTI ID: 15004264
• Report Number(s): NREL/CP-520-33591; TRN: US201015%%449
• Resource Relation: Conference: Presented at the National Center for Photovoltaics and Solar Program Review Meeting, 24-26 March 2003, Denver, Colorado
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
36 MATERIALS SCIENCE
A CENTERS
CATHODOLUMINESCENCE
DEPOSITION
DISTRIBUTION
EMISSION SPECTRA
EXCITONS
GRAIN BOUNDARIES
PASSIVATION
PHYSICS
PROCESSING
RECOMBINATION
SOLAR CELLS
SPATIAL DISTRIBUTION
SPECTRA
STABILITY
THIN FILMS
CADMIUM TELLURIDE
CDTE
CATHODOLUMINESCENCE SPECTROSCOPIC IMAGING
CLSI
Solar Energy - Photovoltaics