Thin films and solar cells of cadmium telluride and cadmium zinc telluride

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1991

OSTI ID:6806272

Ferekides, C S

The objectives of this dissertation are to investigate (1) the metalorganic chemical vapor deposition (MOCVD) and properties of cadmium telluride (CdTe) and cadmium zinc telluride (Cd(1-x)Zn(z)Te) films and junctions, and their potential application to solar cells, and (2) the fabrication and characterization of CdTe solar cells by the close spaced sublimation (CSS) technique. CdTe and Cd(1-x)Zn(x)Te films have been deposited by MOCVD on a variety of substrates at 300-400 C.The effect of the deposition parameters and post deposition heat treatments on the electrical, optical, and structural properties have been investigated. Heterojunctions of the configuration CdTe/transparent conducting semiconductor (TCS) and Cd(1-x)Zn(x)Te/TCS have been prepared and characterized. CdTe(MOCVD)/CdS and Cd(1-x)Zn(x)Te(E sub g = 1.65eV)/Cd(1-x)Zn(x)S solar cells with efficiencies of 9.9 percent and 2.4 percent, respectively have been fabricated. The as-deposited CdTe(MOCVD)/CdS junctions exhibited high dark current densities due to deflects at the interface associated with small grain size. No effective post-deposition heat treatment has been developed. CdTe/CdS solar cells have also been fabricated by the close spaced sublimation (CSS). Significant improvements in material and processing have been made, and in collaboration with fellow researchers an AM1.5 conversion efficiency of 13.4 percent has been demonstrated, the highest efficiency ever measured for such devices. The highest conversion efficiency for the CdTe(CSS)/CdS solar cell was achieved by reaching high open-circuit voltages and fill factors, while the short-circuit current densities were moderate. These results indicate that further improvements to increase the short-circuit current densities can result in conversion efficiencies over 15 percent.

• Research Organization: University of South Florida, Tampa, FL (United States)
• OSTI ID: 6806272
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140501* -- Solar Energy Conversion-- Photovoltaic Conversion
CADMIUM COMPOUNDS
CADMIUM TELLURIDES
CHALCOGENIDES
CHEMICAL COATING
CHEMICAL VAPOR DEPOSITION
CRYSTAL STRUCTURE
CURRENT DENSITY
DEPOSITION
DIRECT ENERGY CONVERTERS
EFFICIENCY
ELECTRICAL PROPERTIES
ENERGY EFFICIENCY
EQUIPMENT
EVAPORATION
FABRICATION
FILMS
GRAIN SIZE
HEAT TREATMENTS
HETEROJUNCTIONS
JUNCTIONS
MICROSTRUCTURE
OPTICAL PROPERTIES
PHASE TRANSFORMATIONS
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
PHYSICAL PROPERTIES
SEMICONDUCTOR DEVICES
SEMICONDUCTOR JUNCTIONS
SIZE
SOLAR CELLS
SOLAR EQUIPMENT
SUBLIMATION
SUBSTRATES
SURFACE COATING
TELLURIDES
TELLURIUM COMPOUNDS
THIN FILMS
ZINC COMPOUNDS
ZINC TELLURIDES