Liquid Phase Epitaxial Growth of GaInp Alloy Thick Layer and its Application

GalnP合金是一种很有前途的绿色发光器件材料。然而，用该合金制成的器件尚未工业化生产。一个很大的障碍是缺乏生长合金的衬底。在本研究中，开发了一种制备基体可用的合金体或厚层的技术。为了获得较厚的生长层，采用了液相生长技术。需要解决的三个问题是：1)P因蒸发从生长溶液中逸出；2)合金生长基质；在这一阶段无法获得衬底，3)生长足够厚的合金的方法，这是通过传统的慢冷却方法无法实现的。实验结果如下：1)采用准气密滑艇。与使用常规敞开式船的情况相比，生长速度可以提高。2)采用两种基材；GaAsP衬底价格昂贵，GaP衬底应用广泛。在GaP衬底和生长的合金层之间存在晶格失配。为了缓解这种不匹配，研究了在GaP衬底上制备阶梯渐变层和连续渐变层的方法。结果表明，在合适的条件下，0.25摩尔分数的组成步骤可以实现层模式生长。在连续分级组合物的实验中，采用慢冷却方法可使组合物从0.95变化到0.61。3)采用溜溜球溶质进料法生长厚层，在GaP衬底上成功生长出厚度为200mum的厚层。使用上述1)、2)和3)技术，可以制造GaInP合金衬底。因此，可以建立开发高效绿色发光二极管的基本技术。

GalnP alloy is a promising material for green-light-emitting devices. However, the devices made from the alloy have not yet been fabricated by industrial manner. A large obstacle is the absence of the substrate to grown the alloy on. In this study, a technique to prepare an alloy bulk or a thick layer available to the the substrate was developed.To obtain a thick grown layer, a liquid phase growth technique was adopted. Three problems to be solved are 1) escape of P from the growth solution due to evaporation, 2) the substrates for the growth of the alloy ; the substrates cannot be obtained in this stage, and 3) the method to grow a sufficiently thick alloy, which can not be achieved by a conventional slow cooling method. The experimental results are as follows. 1) A quasi-air-tight slide boat was used. The growth rate could be increased as compared with the cases using the conventional open-type boat. 2) Two kinds of substrate were adopted ; GaAsP expensive substrates and GaP substrates used widely. A lattice mismatch exists between a GaP substrate and a grown alloy layer. To relax the mismatch, the fabrication of a step-wise graded composition layer and a continuously graded one on the GaP substrate was investigated. It was made clear that the compositional step of 0.25 mole fraction can be allowed for a layer-mode growth under suitable conditions. In the experiments for the continuously graded composition, the composition could be changed from 0.95 to 0.61 by slow-cooling method. 3) The yo-yo solute feeding method was applied to the growth of a thick layer, and the layer with 200mum thickness could be successfully grown on the GaP substrate. Using 1), 2) and 3) techniques mentioned above, GaInP alloy substrates can be fabricated. Thus, the fundamental techniques to develop a high efficiency greenlight-emitting diode could be established.