Photoelectronic properties of zinc phosphide crystals, films, and heterojunctions. Quarterly progress report No. 12, January 1-March 31, 1982
Antiphase domain boundaries and low-angle grain boundaries formed from pile up of dislocations are the two commonly observed defects in sublimation-grown Zn/sub 3/P/sub 2/ crystals by TEM. Except for these two types of defect, the crystals were of good quality and defect free. CdS/Zn/sub 3/P/sub 2/ heterojunctions were prepared by vacuum evaporation deposition of CdS films onto single crystal Zn/sub 3/P/sub 2/. The cells were poor diodes, showing V/sub oc/ of less than 0.1 V even with J/sub sc/ = 8.3 mA/cm/sup 2/. A heat treatment at 450/sup 0/C for 10 min in hydrogen increased V/sub oc/ to 0.55 V, but only at the expense of virtually eliminating the J/sub sc/. CdS/Mg/Zn/sub 3/P/sub 2/ heterojunctions have been prepared with a 50 to 100A Mg film being vacuum deposited on single crystal Zn/sub 3/P/sub 2/, followed immediately by vacuum deposition of a CdS film without breaking vacuum. The CdS film acts to passivate the thin Mg film, serves as front contact, and acts as an anti-reflection coating. The best cell prepared in this way showed V/sub oc/ = 0.50 V, J/sub sc/ = 7.6 mA/cm/sup 2/ and ff = 0.45. Other cells with smaller V/sub oc/ showed J/sub sc/ as high as 11.4 mA/cm/sup 2/. Analysis of the collection function indicates an interface recombination velocity of 1.9 x 10/sup 7/ cm/sec, the same as reported for ZnO/Zn/sub 3/P/sub 2/ heterojunctions. Application of usual junction theory to calculation of the fill factor indicated that the measured values in the range of 0.4 to 0.5 were consistent with observed series and shunt resistance values and the collection function values. From all data to date it seems evident that interface properties of Zn/sub 3/P/sub 2/ are unusually deleterious for junction formation, and that only Mg to date has been successful in reacting with the surface to form a good junction. Investigation of the interface interactions of Zn/sub 3/P/sub 2/ appears critical for further development.
- Research Organization:
- Solar Energy Research Inst., Golden, CO (USA); Stanford Univ., CA (USA). Dept. of Materials Science and Engineering
- DOE Contract Number:
- AC02-77CH00178
- OSTI ID:
- 5348646
- Report Number(s):
- SERI/PR-1202-1-T4; ON: DE82014712
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ZINC PHOSPHIDE SOLAR CELLS
ELECTRICAL PROPERTIES
ZINC PHOSPHIDES
CRYSTAL DEFECTS
HETEROJUNCTIONS
ANTIREFLECTION COATINGS
CADMIUM SULFIDES
CRYSTALS
CURRENT DENSITY
DISLOCATIONS
ELECTRIC CONTACTS
ELECTRIC POTENTIAL
FILL FACTORS
FILMS
GRAIN BOUNDARIES
INTERFACES
LIGHT TRANSMISSION
MAGNESIUM
PASSIVATION
QUANTUM EFFICIENCY
SPECTRAL RESPONSE
VACUUM EVAPORATION
ALKALINE EARTH METALS
CADMIUM COMPOUNDS
CHALCOGENIDES
COATINGS
CRYSTAL STRUCTURE
DIRECT ENERGY CONVERTERS
EFFICIENCY
ELECTRICAL EQUIPMENT
ELEMENTS
EQUIPMENT
EVAPORATION
INORGANIC PHOSPHORS
JUNCTIONS
LINE DEFECTS
METALS
MICROSTRUCTURE
PHASE TRANSFORMATIONS
PHOSPHIDES
PHOSPHORS
PHOSPHORUS COMPOUNDS
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
PHYSICAL PROPERTIES
PNICTIDES
SEMICONDUCTOR JUNCTIONS
SOLAR CELLS
SOLAR EQUIPMENT
SULFIDES
SULFUR COMPOUNDS
ZINC COMPOUNDS
140501* - Solar Energy Conversion- Photovoltaic Conversion