1987 Fiscal Year Final Research Report Summary
Study of ZnS_xSe_<1-x> Blue Light Emitting Diodes
Project/Area Number |
60420020
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Research Category |
Grant-in-Aid for General Scientific Research (A)
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Allocation Type | Single-year Grants |
Research Field |
Applied materials
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Research Institution | Science University of Tokyo |
Principal Investigator |
AOKI Masaharu Science University of Tokyo, Faculty of Industrial Science and Technology, 基礎工学部, 教授 (80010619)
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Co-Investigator(Kenkyū-buntansha) |
YOSHIDA Iwao Science University of Tokyo, Faculty of Engineering, 工学部第一部, 助手 (80084391)
WATANABE Tsuneo Science University of Tokyo, Faculty of Industrial Science and Technology, 基礎工学部, 助教授 (70110947)
SANO Masatoshi Science University of Tokyo, Faculty of Engineering, 工学部第一部, 助教授 (80103068)
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Project Period (FY) |
1985 – 1987
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Keywords | Liquid Phase Epitaxy / Light Emitting Diodes / II-VI Compound Semiconductors / Mixed Crystals / Iodine Transport Method / 溶液成長法 |
Research Abstract |
Single crystals of ZnS and ZnSe for substrate in epitaxial growth were prepared by iodine transport method and solution growth with various solvents. Single Crystals of ZnS with planes of 4x4 mm ^2 were grown by the iodine transport in a vertical furnace. single crystals of ZnS grown from chalcogeni de solution had planes of 5x5 mm ^2. Undoped as-grown single crystals of ZnSe grown by solution growth with Sb_2Te_3 as solvent showed 10^4 cm, which value was relatively small for undoped as-grown ZnS crystal. Single crystals of ZnSe grown from In-Zn-Al solution had low resistivity and large size enough to be used as substrate. Mixed crystals of ZnS_xSe_<1-x> and Zn_xCd_<1-x>S for emission materials in LED were prepared by solution growth from Te solution. The solubility of ZnS to Te solvent was low and the composition of the solution was difficult to select suitably, so that the crystals were not grown in all composition range. In ZnS_xSe_<1-x> system, the peak energy position of the emission due to Te isoelectric traps moved to blue light region, as the concentration of ZnS in solution increased. In Zn_xCd_<1-x>S system, the resistivity decreased as the concentration of CdS in solution increased. Epitaxial layers of ZnS_xSe_<1-x> were grown on ZnS (111)S surface by liquid phase epitaxy using a slide boat. In the growth of ZnSe on ZnS substrate, the layer more smooth than the previous study were obtained at a growth temperature of 790 C and a slow cooling rate of 0.2 C/min. In the epitaxial growth of the mixed crystals, the layer grown had higher concentration of ZnS than that of the solution. The growth of ZnSe on ZnSe substrate failed to get the smooth surface, because of the heavy melt-back of the substrate by molten Te.
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