Thin film cadmium telluride solar cells. Progress report, 1 October 1983-30 September 1984

Technical Report · Mon Apr 01 04:00:00 EST 1985

OSTI ID:5750003

Chu, T L

During this reporting period, the deposition of CdTe films by the direct combination of the Cd and Te vapor on foreign substrates has been continued with emphasis on the resistivity control of p-type films and the reduction of p-CdTe/substrate interface resistance. CdTe films deposited on graphite substrates were all p-type, irrespective of the substrate temperature and the reactant composition. This result indicates that carbon is incorporated into CdTe presumably thru its reaction with Te and that carbon is electrically active in CdTe. Using W/graphite as substrates, the change in conductivity type of nearly stoichiometric films has been found to take place over a very narrow range of the reactant composition. In addition to using a Cd-deficient reactant mixture, the resistivity of p-type CdTe films may also be controlled by adding a dopant to the reactant mixture. The effect of reactant composition and substrate temperature on the resistivity of the reactant mixture was studied in detail. The effect of adding oxygen to the reactant was also investigated. Using CdTe films deposited on Corning 7059 glass substrates, the optical band gap of CdTe films was found to be 1.50 eV at room temperature. The preparation and characterization of thin film cadium telluride heterojunction solar cells have been continued. The open-circuit voltage (up to 0.75V) and short-circuit current density (up to 20mA/cm/sup 2/) are reasonably reproducible; however, the high p-CdTe/substrate interface resistance remains to be a problem in the fabrication of thin film CdTe solar cells. Because of the uncontrolled series resistance, the best CdS/CdTe cells have an AM1 efficiency of about 6.5% and the best ITO/CdTe cell has an AM1 efficiency of about 8%. Further work will be directed to the use of inverted structures.

• Research Organization: Southern Methodist Univ., Dallas, TX (USA)
• DOE Contract Number: AC02-83CH10093
• OSTI ID: 5750003
• Report Number(s): SERI/STR-211-2673; ON: DE85008803
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140501* -- Solar Energy Conversion-- Photovoltaic Conversion
CADMIUM COMPOUNDS
CADMIUM OXIDES
CADMIUM SULFIDES
CADMIUM TELLURIDE SOLAR CELLS
CHALCOGENIDES
CHEMICAL COATING
CHEMICAL VAPOR DEPOSITION
DEPOSITION
DESIGN
DIRECT ENERGY CONVERTERS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
EQUIPMENT
FABRICATION
FILMS
HETEROJUNCTIONS
INORGANIC PHOSPHORS
JUNCTIONS
OPTICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
PHOSPHORS
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
PHYSICAL PROPERTIES
RESEARCH PROGRAMS
SEMICONDUCTOR JUNCTIONS
SOLAR CELLS
SOLAR EQUIPMENT
SULFIDES
SULFUR COMPOUNDS
SURFACE COATING
SYSTEMS ANALYSIS
TESTING
THIN FILMS