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Title: Preparation and properties of evaporated CdTe films compared with single crystal CdTe. Progress report No. 4, August 1-October 31, 1981

Abstract

The hot-wall vacuum evaporation system is nearly complete and the first films are expected in early December. CdTe homojunction cells were theoretically modelled and to some extent tested experimentally using the n-type CdTe film on p-type CdTe crystal homojunction cells previously deposited at Linz. Modelling emphasizes the known importance of surface recombination velocity for such homojunction cells. The n-type layer on the experimental cell was thinned by etching from 5 micrometers to 1.5 micrometers, with a corresponding increase in short-circuit current from 0.1 to 1 mA/cm/sup 2/. This behavior is as theoretically expected; to obtain a short-circuit current of 11 mA/cm/sup 2/, as required for a 10% cell, requires a thickness of about 0.2 micrometers for a surface recombination velocity of 10/sup 6/ cm/sec and other realistic cell parameters. By doping experiments on single crystal CdTe, it has been shown that the hole density does decrease when the P dopant density is decreased below a critical value in CdTe:P crystals, thus eliminating the possibility that the major acceptors in the P-doped crystals were not P impurity. Attempts to heavily dope CdTe with As were less successful, but this may be due to the use of elemental As as the dopantmore » in this case rather than a compound of the dopant. Cs was shown to be an effective dopant of CdTe and resistivities as low as 0.3 ohm-cm corresponding to hole densities in the low 10/sup 17/ cm/sup -3/ range were obtained. An apparent correlation between the low-temperature barrier height associated with a grain boundary in CdTe and the angle of mismatch between the two grains has been observed. Improved capacitance of grain boundary measurements should yield defect densities.« less

Authors:
Publication Date:
Research Org.:
Solar Energy Research Inst., Golden, CO (USA)
OSTI Identifier:
5627195
Report Number(s):
SERI/PR-9330-1-T4
ON: DE82003925
DOE Contract Number:  
AC02-77CH00178
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; CADMIUM TELLURIDE SOLAR CELLS; RECOMBINATION; CADMIUM TELLURIDES; CRYSTAL DOPING; GRAIN BOUNDARIES; ARSENIC ADDITIONS; CAPACITANCE; CARRIER DENSITY; CESIUM ADDITIONS; CRYSTAL DEFECTS; ELECTRIC CURRENTS; ETCHING; HOMOJUNCTIONS; MONOCRYSTALS; N-TYPE CONDUCTORS; PHOSPHORUS ADDITIONS; VACUUM EVAPORATION; ALLOYS; ARSENIC ALLOYS; CADMIUM COMPOUNDS; CESIUM ALLOYS; CHALCOGENIDES; CRYSTAL STRUCTURE; CRYSTALS; CURRENTS; DIRECT ENERGY CONVERTERS; ELECTRICAL PROPERTIES; EQUIPMENT; EVAPORATION; JUNCTIONS; MATERIALS; MICROSTRUCTURE; PHASE TRANSFORMATIONS; PHOTOELECTRIC CELLS; PHOTOVOLTAIC CELLS; PHYSICAL PROPERTIES; SEMICONDUCTOR JUNCTIONS; SEMICONDUCTOR MATERIALS; SOLAR CELLS; SOLAR EQUIPMENT; SURFACE FINISHING; TELLURIDES; TELLURIUM COMPOUNDS; SOLAR; CDTE FILMS; EVAPORATED; SINGLE CRYSTAL; 140501* - Solar Energy Conversion- Photovoltaic Conversion

Citation Formats

Bube, R H. Preparation and properties of evaporated CdTe films compared with single crystal CdTe. Progress report No. 4, August 1-October 31, 1981. United States: N. p., 1981. Web. doi:10.2172/5627195.
Bube, R H. Preparation and properties of evaporated CdTe films compared with single crystal CdTe. Progress report No. 4, August 1-October 31, 1981. United States. doi:10.2172/5627195.
Bube, R H. Thu . "Preparation and properties of evaporated CdTe films compared with single crystal CdTe. Progress report No. 4, August 1-October 31, 1981". United States. doi:10.2172/5627195. https://www.osti.gov/servlets/purl/5627195.
@article{osti_5627195,
title = {Preparation and properties of evaporated CdTe films compared with single crystal CdTe. Progress report No. 4, August 1-October 31, 1981},
author = {Bube, R H},
abstractNote = {The hot-wall vacuum evaporation system is nearly complete and the first films are expected in early December. CdTe homojunction cells were theoretically modelled and to some extent tested experimentally using the n-type CdTe film on p-type CdTe crystal homojunction cells previously deposited at Linz. Modelling emphasizes the known importance of surface recombination velocity for such homojunction cells. The n-type layer on the experimental cell was thinned by etching from 5 micrometers to 1.5 micrometers, with a corresponding increase in short-circuit current from 0.1 to 1 mA/cm/sup 2/. This behavior is as theoretically expected; to obtain a short-circuit current of 11 mA/cm/sup 2/, as required for a 10% cell, requires a thickness of about 0.2 micrometers for a surface recombination velocity of 10/sup 6/ cm/sec and other realistic cell parameters. By doping experiments on single crystal CdTe, it has been shown that the hole density does decrease when the P dopant density is decreased below a critical value in CdTe:P crystals, thus eliminating the possibility that the major acceptors in the P-doped crystals were not P impurity. Attempts to heavily dope CdTe with As were less successful, but this may be due to the use of elemental As as the dopant in this case rather than a compound of the dopant. Cs was shown to be an effective dopant of CdTe and resistivities as low as 0.3 ohm-cm corresponding to hole densities in the low 10/sup 17/ cm/sup -3/ range were obtained. An apparent correlation between the low-temperature barrier height associated with a grain boundary in CdTe and the angle of mismatch between the two grains has been observed. Improved capacitance of grain boundary measurements should yield defect densities.},
doi = {10.2172/5627195},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1981},
month = {10}
}

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