Zn/sub 3/P/sub 2/ as an improved semiconductor for photovoltaic solar cells. Third quarterly report, March 1-May 31, 1979
Heterojunctions of the type p-Zn/sub 3/P/sub 2//n-(Cd/sub x/Zn/sub 1-x/)/sub 3/P/sub 2/ were fabricated and tested by interdiffusing the end members of the alloy system. Grading of the junction was evidenced by electron microprobe analysis of the metallurgical junction. The current-voltage dependence of the diodes has been examined as a function of temperature and a simple heterojunction model yields a diffusion voltage of 0.64 eV at room temperature, only slightly less than Schottky barrier devices and approx. 0.2 eV greater than that obtained with abrupt junction devices. The optical absorption constant of several alloys has been examined and the expected decrease in Eg with addition of cadmium is found. The bandgap at the p-n transition is estimated to be near 1.1 eV. The dependence of J/sub sc/ on grid width of Schottky barrier devices has been compared to theory and the effective diffusion length in thin Zn/sub 3/P/sub 2/ films calculated. The data suggest a junction collection efficiency on the order of 50%. The minority carrier diffusion length has also been measured by EBIC and laser scanning on the same sample and the results compared. The front wall spectral response method has also been used to determine L/sub n/. The range of minority carrier diffusion lengths observed by all methods is between 0.5 ..mu..m to 4 ..mu..m. On the basis of these values, current densities of between 10 to 23 mA/cm/sup 2/ are expected for a conventional backwall device and 3-16.7 mA/cm/sup 2/ for a Schottky barrier grid device. The fabrication of a novel ion plated substrate useful for the high temperature growth of Zn/sub 3/P/sub 2/ films is also reported.
- Research Organization:
- Delaware Univ., Newark (USA). Inst. of Energy Conversion
- DOE Contract Number:
- AC02-77CH00178
- OSTI ID:
- 6721651
- Report Number(s):
- SERI/PR-8062-1-T4
- Country of Publication:
- United States
- Language:
- English
Similar Records
Improved semiconductors for photovoltaic cells. Quarterly report No. 9, July 1-September 1, 1978
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Related Subjects
36 MATERIALS SCIENCE
ZINC PHOSPHIDE SOLAR CELLS
FABRICATION
ZINC PHOSPHIDES
DIFFUSION LENGTH
SEMICONDUCTOR JUNCTIONS
CURRENT DENSITY
DIFFUSION
ELECTRICAL PROPERTIES
ENERGY GAP
SCHOTTKY BARRIER DIODES
SPECTRAL RESPONSE
SUBSTRATES
DIMENSIONS
DIRECT ENERGY CONVERTERS
EQUIPMENT
JUNCTIONS
LENGTH
PHOSPHIDES
PHOSPHORUS COMPOUNDS
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
PHYSICAL PROPERTIES
PNICTIDES
SEMICONDUCTOR DEVICES
SEMICONDUCTOR DIODES
SOLAR CELLS
SOLAR EQUIPMENT
ZINC COMPOUNDS
140501* - Solar Energy Conversion- Photovoltaic Conversion
360601 - Other Materials- Preparation & Manufacture