Degree Granting Department
Christos S. Ferekides.
tandem solar cells, wideband gap semiconductors, thin films, CZT
High efficiency solar cells can be attained by the development of two junctions one stacked on top of each other into tandem structures. So that, if a photon is not able to excite an electron-hole pair in the top cell can create a pair in the bottom cell, which has a smaller bandgap. For a two junction tandem device structure, the bandgap of the top cell should be 1.6-1.8eV and for the bottom cell should be 1eV to attain efficiencies in the range of 25%. Cadmium Zinc Telluride which has a tunable bandgap of 1.45- 2.2eV is a candidate for the top cell of the tandem structure. Cadmium Zinc Telluride (Cdâ-xZnxTe) films were deposited by co-sputtering of CdTe and ZnTe. Deposition of Cdâ-xZnxTe was studied in Ar and Ar/Nâ ambient.
Characterization of the films was done using transmission response, X-ray diffraction (XRD), Atomic Force Microscopy (AFM), Secondary Electron Microscopy (SEM), current-voltage (I-V) and spectral response measurements. CZT deposited on CdS/SnOâ substrates showed improved performance compared to other heterojunction partners. Doped graphite and copper were utilized as back contacts for CZT devices. Post deposition annealing treatments with ZnClâ on CZT films were done and their effect on the devices was also studied. The best combination of Voc and Jsc were 530mV and 3.66mA/cmÂ² respectively.
Scholar Commons Citation
Subramanian, Senthilnathan, "Characterization of cadmium zinc telluride solar cells by RF sputtering" (2004). Graduate Theses and Dissertations.