Graduation Year

2004

Document Type

Thesis

Degree

M.S.E.E.

Degree Granting Department

Electrical Engineering

Major Professor

Christos S. Ferekides, Ph.D.

Committee Member

Don Morel, PhD.

Committee Member

Yun L. Chiou, PhD.

Keywords

CZT, Thin films, Processing, TCO, Superstrate configuration

Abstract

Cadmium Zinc Telluride (CdxZn1-xTe or CZT) is a ternary semiconductor with a tunable bandgap of 1.44-2.26 eV. Solar cells with efficiencies of 20% or higher can be achieved by using a tandem solar cell structure which consists of a top cell and a bottom cell connected in series. In this kind of a structure, the light passes through the top cell first which has a wider bandgap to absorb light of shorter wavelengths and the remaining light passes through the bottom cell with a lower bandgap to absorb light of higher wavelengths. For a tandem cell structure, the ideal bandgap for the top and bottom cell is 1.7 eV and 1 eV respectively. Cadmium Zinc Telluride is a suitable candidate for the top cell and Copper Indium Gallium Diselenide (CIGS) with a bandgap of around 1 eV is a suitable candidate for the bottom cell.

This work involves characterization and optimization of CZT solar cells by Close Spaced Sublimation (CSS). Cadmium Zinc Telluride is deposited by the co sublimation of Cadmium Telluride (CdTe) and Zinc Telluride (ZnTe) chunks. Cadmium Zinc Telluride solar cells were fabricated using Tin Oxide (SnO2), Zinc Oxide (ZnO) and Zinc Stannate (Zn2SnO4) films as substrates. The as-deposited CZT films were studied by XRD, EDS and SEM measurements. The devices were characterized by Current-Voltage (I-V) and Spectral Response measurements.

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