Development of wide bandgap II--VI materials for visible lasers and light emitting diodes. A. Bipolar doping and electroluminescence of ZnMgCdSe structures. B. Hexagonal ZnSe-based structures.
Item
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Title
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Development of wide bandgap II--VI materials for visible lasers and light emitting diodes. A. Bipolar doping and electroluminescence of ZnMgCdSe structures. B. Hexagonal ZnSe-based structures.
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Identifier
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AAI9959201
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identifier
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9959201
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Creator
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Lin, Wei-Cheng Wilson.
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Contributor
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Adviser: Maria C. Tamargo
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Date
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2000
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Language
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English
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Publisher
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City University of New York.
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Subject
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Engineering, Materials Science
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Abstract
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Wide bandgap Zn1-x-yMgxCdySe system grown on InP substrates has potential for making visible light emitting devices. Bipolar doping of Zn1-x-yMgxCd ySe (cladding and waveguide layers) and growth of lattice-matched p-type contact layer (ZnSe0.53Te0.47) are essential. The n-type doping of Zn1-x-yMgxCdySe has been achieved by using chlorine with the maximum free electron concentrations in the range of 1018 cm-3 and mobilities of about 300 cm2/Vs. p-type doping of Zn1-x-y MgxCdySe has been performed using a radio frequency (rf) discharge N plasma source. The net acceptor (NAND) level is currently limited to 1 x 1016 cm-3 . p-type doping of ZnSe, Zn1-xMgxSe and Zn1-yCdySe was studied separately. The results suggest that Mg and Cd both hinder the p-type doping of Zn1-x-y MgxCdySe. Delta (delta)-doping techniques are applied to enhance the p-type doping level of ZnSe. In particular, by using a novel triple (N+Te)delta-doping, the (NA-ND) level is dramatically increased from 3 x 1017 to 6 x 1018cm-3. Based on these results, we propose a way to increase the p-type doping of the quaternary involving modulation doping.;MBE growth of high quality ZnSe1-xTex alloys and their nitrogen doping were studied as a function of Te concentration. In particular, N doped ZnSe0.53Te0.47 lattice-matched to 10 substrates can have a free hole concentration as high as 2 x 10 19 cm-3. The I-V characteristics between two Au contacts on the highly N doped ZnSe0.53Te0.47 layer show ohmic behavior. This demonstrates that the ZnSe0.53Te 0.47 layer can be used as an ideal p-type ohmic contact layer for the ZnCdSe/ZnMgCdSe QW lasers and LEDs. Full-color LEDs have been fabricated by combining these accomplishments.;MBE growth of ZnSe single layers and ZnCdSe/ZnSe QW structures and nitrogen doping of ZnSe have also been performed on novel hexagonal ZnxMg 1-xSySe1-y II-VI substrates. Cross-sectional transmission electron microscopy (TEM) analysis demonstrates that hexagonal ZnSe has been achieved by using these hexagonal substrates. Photoluminescence studies suggest that nitrogen atoms have introduced acceptor levels in these hexagonal ZnSe samples and these samples were heavily doped (or highly compensated). We propose to optimize the N source conditions or use different growth planes for a more reasonable N incorporation in these hexagonal ZnSe.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
