| AVS 62nd International Symposium & Exhibition | |
| Surface Science | Thursday Sessions |
| Session SS+AS+EM+EN-ThA |
| Session: | Atomistic Modeling of Surface Phenomena & Semiconductor Surfaces and Interfaces - II |
| Presenter: | Mohit Tuteja, University of Illinois at Urbana Champaign |
| Authors: | M. Tuteja, University of Illinois at Urbana Champaign P. Koirala, University of Toledo J. Soares, University of Illinois at Urbana Champaign R. Collins, University of Toledo A. Rockett, University of Illinois at Urbana Champaign |
| Correspondent: | Click to Email |
Device quality CdS/CdTe heterostructures and completed solar cells (~12% efficient) have been studied using low-temperature photoluminescence (PL) as a function of temperature (82-295 K) and laser excitation power (0.02-2 mW). The CdS/CdTe junctions were grown on transparent conducting oxide covered soda lime glass using rf-sputter deposition. It was found that the luminescence shifts from being dominated by sub-gap defect-mediated emission at lower excitation powers to near band edge excitonic emission at higher excitation powers. The effect of copper (Cu) used in making back contacts was studied in connection with the CdS/CdTe junction PL. It was found that the presence of Cu suppresses the sub-band gap PL emissions. This effect was concluded to be due either to Cu occupying cadmium vacancies (VCd) or forming acceptor complexes with them. This points to a potential role of Cu in plugging sub-band gap recombination routes and hence increasing charge separation ability of the device. An energy band diagram is presented indicating various observed transitions and their possible origins.