Detection of Efficiency-Limiting Defects in Cadmium Telluride
Open Access
Author:
Coda, Anthony Bernard
Area of Honors:
Engineering Science
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
Dr. Patrick M Lenahan, Thesis Supervisor Judith A Todd Copley, Thesis Honors Advisor
Keywords:
CdTe Cadmium Telluride Electron Paramagnetic Resonance EPR Solar
Abstract:
Cadmium telluride is one of the leading materials in thin-film solar cell technologies. CdTe solar
cells have one of the highest theoretical efficiencies of all materials. However, efficiencies are
currently limited due to deep-level defects acting as recombination centers. It is currently not
well understood how the properties of different dopants contribute to the introduction of new
defects or augmentation of existing intrinsic defects. In this study, Electron Paramagnetic
Resonance (EPR) is used to characterize the defects present in undoped, p-type, and n-type
CdTe. The differences in the EPR spectra for differently doped samples provides evidence that
particular dopants may not be well suited for solar cell applications. Most notably, EPR signals
in As-doped CdTe may have indicated a significant concentration of tellurium vacancies, which
may act as efficiency-limiting recombination centers in solar cell applications due to their energy
level near the center of the CdTe band gap.
