1987 Fiscal Year Final Research Report Summary
Growth of Semi-Insulating Cadmium Telluride by The Bridgman Method
| Project/Area Number |
61550234
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
電子材料工学
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| Research Institution | Kansai University |
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Principal Investigator |
YOKOTA Katsuhiro Faculty of Engineering,Kansai University,Professor, 工学部, 教授 (50067617)
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| Co-Investigator(Kenkyū-buntansha) |
TAMURA Susumu Faculty of Engineefing,Kansai University,Assistant, 工学部, 助手 (10067754)
KATAYAMA Saichi Faculty of Engineefing,Kansai University,Professor, 工学部, 教授 (90067398)
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| Project Period (FY) |
1986 – 1987
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| Keywords | Compound Semiconductors / Impurity / 電気特性 |
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| Research Abstract |
Single crystal CdTe is employed for the fabrication of radiation detectors, orptical and acousto-optic modulators,infrared windows.Also it is used as a substrate for the epitaxial growth of mercury cadmium telluride.Very high resistiviies are required for the substrate materials.Large ingots of CdTe are generally prepared using the Bridbman furnace from a melt containing Te amounts more than stoichometry constitution.The CdTe have a low resistivity p-type material.However a traveling heater method is used to prepare undoped bulk crystal CdTe with resistivities of 10^6-10^8 cm.
CdTe was made in quartz ampoules evacuated into 2 X 10^5and 3 X10^7 torr using a horizontal Bridgman furnace.High vacuum in the ampoiles resulted in high resistivity CdTe of 10^6-10^8 cm. On the other hand low vacuum resulted in low resistivity CdTe of 10-10^3 cm.Twenty-five impurities were analysed using an atomic absorption spectrophotometer and an inductively coupled plasma spectrometer. There was no remarkable difference in the impurity concentrations between the prepared CdTe.The impurities was no effects on the resistivity.However the activation energy of carriers in the low resistivity CdTe represented that the carriers were induced from impurities such as antimon,chromium and phosphorus. The oxygen concentration in the CdTe decreased with increasing the residual gas pressure in the ampoules.The low resistivity CdTe had oxygen at high concentrations. Also the intensities of the 1.45 and 1.555 eV emission in photoluminescences increased with increasing the residual gas pressure.The low resistivity CdTe is found to have Cd vacancies at high concentrations.Thus oxygen in CdTe contributes to increase the concentrations of the Cd vacancies and of antimony,chromium and phosphorus occupied on Te sites.
We had conclusion that vacuum in the ampoules must be high for pewpeinf hifh resistivity CdTe.
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Research Products
(6 results)
