Thermodynamic Database for Alloy Semiconductor Systems.

III-V族化合物半导体（III= Al，Ga，In：V=P，As，Sb）具有Si半导体所不能获得的各种优异性能。此外，被称为III-V族晶体合金半导体的这些化合物的混合物提供了通过其组成任意控制其物理性质（诸如带隙能量和晶格常数）的可能性。因此，III-V族晶体合金半导体在光电子学和高速器件方面具有重要意义。为了实现所需的性能，即，摘要为了在近相平衡条件下用液相外延（LPE）法制备出成分合适的晶态合金，必须要有相图来控制其微观结构和成分。然而，据报道，衬底上的薄外延层表现出与体材料完全不同的相平衡，例如，平衡成分的偏离，意外相的形成， 关于我们 本文根据热力学数据和实验结果，对III-V族晶体合金半导体的相平衡进行了热力学分析。然后建立了计算体相和薄层相平衡的热力学数据库，液相和化合物的吉布斯自由能分别用亚正规溶液近似和双子格模型描述。在计算衬底上外延层的稳定性时考虑了应变能，计算了11个三元系的热力学参数，建立了考虑和不考虑应变能的III-V族合金半导体热力学数据库。例如，当GaAs-GaSb晶体合金在InP衬底的（100）面上外延生长时，可以看到由晶体层和衬底之间的外延引起的应变能的效果。根据计算结果，当其厚度为100 μ m，成分为51mol%GaAs时，出现了意想不到的均匀相，这与晶格匹配成分相对应。这与Quillec等人的LPE实验结果相一致。对各种薄膜与衬底组合的计算结果表明，外延层的相稳定性取决于衬底的晶格常数和晶体取向以及外延层的厚度。少

III-V compound semiconductors (III=AI, Ga, In : V=P, As, Sb) have various outstanding properties which can not be obtained by Si semiconductor. Furthermore, mixture of these compounds which is called as III-V crystal alloy semiconductor gives possibilities to control its physical properties arbitrarily such as the band gap energy and the lattice constant by its composition. Therefore, III-V crystal alloy semiconductors are of great significance for opto-electronics and high-speed devices. In order to realize the desirable properties, i.e., to create the crystal alloy with appropriate composition by Liquid Phase Epitaxy (LPE) method under the condition of near phase equilibria, phase diagrams are indispensable for controlling their microstructures and compositions. However, it was reported that a thin epitaxial layer on a substrate exhibited completely different phase equilibria from those of bulk materials, for instance, deviation of equilibrium composition, formation of unexpected pha … More ses and so on. In this research, thermodynamic analysis on the phase equilibria of III-V crystal alloy semiconductor was carried out based on the thermodynamic data and experimental results. Then, thermodynamic database has been established for calculating the phase equilibria of both bulk and thin layer materials.Gibbs energies of the liquid phase and the compound are described by the sub-regular solution approximation and the two-sublattice model respectively. The strain energy was taken into account for calculating the stability of a thin epitaxial layer grown on a substrate.Thermodynamic parameters of eleven ternary systems have been evaluated and thermodynamic database for III-V alloy semiconductors has been constructed with or without taking account of a strain energy between a epitaxial layer and a substrate. The effect of the strain energy which is caused from the epitaxy between a crystal layer and a substrate can be seen, for instance, when a GaAs-GaSb crystal alloy is grown epitaxially on the (100) plane of lnP substrate. According to the result of calculations, unexpected homogeneous phase appears when its thickness is him and its composition is 5 lmol% GaAs which corresponds to the lattice matching composition. This is in good agreement with the experimental result of LPE by Quillec et al. The results of calculations for various combinations between thin layers and substrates show that phase stability of an epitaxial layer depends on the lattice constant and the crystal orientation of the substrate and on the thickness of the epitaxial layer. Less