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Study of ZnS_xSe_<1-x> Blue Light Emitting Diodes

ZnS_xSe_<1-x>蓝光发光二极管的研究

基本信息

批准号：
60420020
负责人：
AOKI Masaharu
金额：
$ 13.12万
依托单位：
Science University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1987
项目状态：
已结题

项目摘要

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.

采用碘输运法和不同溶剂溶液生长法制备了ZnS和ZnSe外延生长衬底单晶。在垂直炉中用碘输运法生长出了平面尺寸为4 × 4 mm ^2的ZnS单晶。从硫族化物溶液中生长的ZnS单晶具有5 × 5 mm ^2的晶面。以Sb_2Te_3为溶剂的溶液法生长的未掺杂的ZnSe单晶体的cm值为10^4，该值相对于未掺杂的ZnS单晶体来说较小。用In Zn Al溶液生长的ZnSe单晶具有低电阻率和大尺寸，可以用作衬底，用Te溶液生长的ZnS xSe<1-x>和Zn xCd <1-x>S混合晶体可以用作LED发光材料。ZnS在Te溶剂中的溶解度较低，溶液的组成难以选择，因此晶体不能在所有组成范围内生长。在ZnS_xSe_2体系中<1-x>，随着溶液中ZnS浓度的增加，Te等电陷阱发射的峰值能量位置向蓝光区移动。在Zn_xCd_<1-x>S体系中，电阻率随溶液中CdS浓度的增加而减小，<1-x>采用滑舟液相外延法在ZnS（111）S表面生长了ZnS_xSe_3外延层。在ZnS衬底上生长ZnSe时，生长温度为790 ℃，冷却速度为0.2 ℃/min时，得到的层比以前的研究更光滑。在混晶外延生长中，生长的层比溶液中的ZnS浓度高。在ZnSe衬底上生长ZnSe，由于Te熔体对衬底的回熔严重，不能得到光滑的表面。