Thin film polycrystalline silicon solar cells. Final report, January 1-December 31, 1979

Technical Report · Mon Jan 01 04:00:00 EST 1979

OSTI ID:5355565

Ghosh, A K; Feng, T; Maruska, H P

A theory of the electrical and photovoltaic properties of polycrystalline silicon is presented. In this theory it is shown that grain boundary states play a dominant role in determining these properties of silicon. Since the grain boundary area is proportional to the grain size, these properties are related to the grain sizes. The recombination loss at grain boundaries is the predominant loss mechanism in polycrystalline solar cells. For small grain sizes, the grain boundary recombination centers affect the minority carrier lifetime more than the dopant even at large concentrations. One could fabricate 10% efficiency polycrystalline solar cells with 20 ..mu..m thick material if the grain sizes were greater than 500 ..mu..m .The results show that tremendous improvements in device performance can be achieved either by increasing the grain size or passivating the grain boundary states to reduce the number of recombination centers. The details of the fabrication procedures for making SnO/sub 2//n-Si, ITO/n-Si, MIS and diffused p/n junction solar cells are presented. The effects of grain boundaries on the generation of photocurrent were studied in the Scanning Electron Microscope using the EBIC technique. In addition to using the intensity modulated mode, a y- modulation technique, which gave more details, was used in the EBIC studies. By studying the Hall mobility of polysilicon in the dark and under illumination, we have developed a phenomenological theory which is capable of explaining the observed resistivity and mobility results. A comparison of the spectral response curves of SnO/sub 2//n-Si heterojunction ad diffused p/n junction cells indicates a lower diffusion length in the diffused cells.

• Research Organization: Exxon Research and Engineering Co., Linden, NJ (USA). Advanced Energy Systems Labs.
• DOE Contract Number: AC03-79ET23047
• OSTI ID: 5355565
• Report Number(s): DOE/ET/23047-4
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140501* -- Solar Energy Conversion-- Photovoltaic Conversion
CARRIER LIFETIME
CARRIER MOBILITY
CHALCOGENIDES
CRYSTAL STRUCTURE
CRYSTALS
DIFFUSION LENGTH
DIRECT ENERGY CONVERTERS
EFFICIENCY
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTRON MICROSCOPY
ELEMENTS
EQUIPMENT
FABRICATION
FILMS
GRAIN BOUNDARIES
GRAIN SIZE
INDIUM COMPOUNDS
INDIUM OXIDES
JUNCTIONS
LIFETIME
MATHEMATICAL MODELS
MICROSCOPY
MICROSTRUCTURE
MIS TRANSISTORS
MOBILITY
OXIDES
OXYGEN COMPOUNDS
P-N JUNCTIONS
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
PHOTOVOLTAIC EFFECT
PHYSICAL PROPERTIES
PHYSICS
POLYCRYSTALS
RECOMBINATION
SCANNING ELECTRON MICROSCOPY
SEMICONDUCTOR DEVICES
SEMICONDUCTOR JUNCTIONS
SEMIMETALS
SILICON
SILICON SOLAR CELLS
SIZE
SOLAR CELLS
SOLAR EQUIPMENT
SOLID STATE PHYSICS
SPECTRAL RESPONSE
TIN COMPOUNDS
TIN OXIDES
TRANSISTORS