Photoelectronic properties of zinc phosphide crystals, films and heterojunctions. Quarterly progress report no. 10, July 1-September 30, 1981
Detailed measurements of current vs voltage have been made as a function of temperature for thick (5000 A) Mg layers on Zn/sub 3/P/sub 2/ single crystals, prepared either by sublimation or by iodine-transport. The junction formed on the sublimation grown crystal shows evidence of a diffused junction with transport controlled by almost pure tunneling. The junction formed on the iodine-transport grown crystal on the other hand, behaves like an abrupt junction with transport controlled by thermally assisted tunneling corresponding to a surface acceptor density of 10/sup 19/ cm/sup -3/ and a barrier height of 1.07 eV. A computer program has been prepared for the HP-85 to permit direct analysis of current vs voltage measurements on these junctions as a function of temperature. Values of J/sub 0/ and ..cap alpha.., as well as testing of different transport models, can be obtained via this program. AC (80 Hz) photoconductivity spectral response curves have been measured on seven single crystal samples of Zn/sub 3/P/sub 2/, prepared by different preparation techniques, and subjected to different heat treatments and surface treatments prior to measurement, over the spectral range from 0.6 to 1.2 micrometers. Surface ac photoconductivity lifetimes range from 0.4 to 40 x 10/sup -6/ sec, and bulk ac photoconductivity lifetimes range from 3 to 100 x 10/sup -6/ sec. Major contributions to the photoconductivity near the band edge of Zn/sub 3/P/sub 2/ come from transitions of about 1.41 eV and 1.52 eV, probably corresponding to direct transitions from the two higher-lying valence bands split by spin-orbit and crystal fields. Use of the ac technique means that slower photoconductivity components, typical of some dc measurements, are excluded from the present measurements.
- 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:
- 6256420
- Report Number(s):
- SERI/PR-1202-1-T2; ON: DE82002459
- Country of Publication:
- United States
- Language:
- English
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Photoelectronic properties of zinc phosphide crystals, films and heterojunctions. Quarterly progress report No. 8, January 1-March 31, 1981
Spectral response of ac photoconductivity in Zn/sub 3/P/sub 2/
Related Subjects
ZINC PHOSPHIDES
ELECTRICAL PROPERTIES
PHOTOCONDUCTIVITY
CHARGE TRANSPORT
COMPUTER CODES
ELECTRIC CURRENTS
ELECTRIC POTENTIAL
ENERGY GAP
HEAT TREATMENTS
HETEROJUNCTIONS
MAGNESIUM
MONOCRYSTALS
SPECTRAL RESPONSE
SURFACE TREATMENTS
TEMPERATURE EFFECTS
TUNNEL EFFECT
ALKALINE EARTH METALS
CRYSTALS
CURRENTS
ELECTRIC CONDUCTIVITY
ELEMENTS
JUNCTIONS
METALS
PHOSPHIDES
PHOSPHORUS COMPOUNDS
PHYSICAL PROPERTIES
PNICTIDES
SEMICONDUCTOR JUNCTIONS
ZINC COMPOUNDS
140501* - Solar Energy Conversion- Photovoltaic Conversion