Development of Photo-Voltaic Cells using III-V Alloy Semiconductors for Thermo-Photo-Voltaic Applications (2004)

目前研究的主要目标是发展新的技术来生长均匀的In_xGa_As和In_xGa_Sb三元块体晶体和高质量的外延层，用于热光电（TPV）能量转换系统的制造。<1-x><1-x>在这方面，主要进行了以下实验研究和分析：1.在飞机和落塔实验中研究了In_xGa_Sb晶体在微重力条件下的晶化过程。<1-x>观察到固液界面的形状和晶体的成分分布受重力的影响。模拟结果表明，在晶体生长过程中，溶质自然对流和溶质Marangoni对流的作用非常显著。2.通过对溶液温度梯度和生长速率的优化，采用冷源和籽晶，在GaSb或InSb籽晶上生长出了均匀的In_xGa_Sb块体晶体。<1-x>In_xGa_&lt;1- ...更多信息 用旋转布里奇曼法在GaAs籽晶上生长了x&gt; As（x = 0.12）单晶。由于在In-Ga-As溶液中连续注入GaAs源材料，生长出的晶体x值均匀。3.采用桥层生长技术，成功地在III-V族二元衬底上生长出了高质量的In_xGa_As外延层。<1-x>在高铟组分In_xGa_As外延层的生长中，采用了一种新的"组分转换"技术。<1-x>生长出铟含量高达80%的高质量外延层。4.首次发展了两种在III-V族衬底上生长低蚀坑密度In_xGa_Sb和In_xGa_As锥形外延层的选择性生长技术，<1-x><1-x>空心锥外延技术，以及成分转换和空心锥外延技术的结合。为了使金字塔外延层在光学器件中得到应用，本文详细研究了Te杂质对GaSb金字塔外延层结构特性的影响。5.采用Zn扩散技术在n型GaSb衬底上生长了p型GaSb外延层。在不同的退火条件下获得的外延层的组成分布。少

The main objectives of the on going research are to develop new techniques to grow homogeneous In_xGa_<1-x>As and In_xGa_<1-x>Sb ternary bulk crystals and high quality epitaxial layers for the fabrication of Thermo-Photo-Voltaic (TPV) energy conversion system. In this aspect, the following experiments have been carried out and analyzed.1.The crystallization process of In_xGa_<1-x>Sb crystals has been investigated under microgravity in an airplane and a drop tower experiments. It is observed that the shape of solid-liquid interface and the composition profile of the crystals are influenced by gravity. Simulation results have shown that the effects of solutal natural convection and solutal Marangoni convection are very significant during the growth of the crystals.2.Homogeneous In_xGa_<1-x>Sb bulk crystals have been grown on GaSb or InSb seeds by cooling source and seed crystals at the optimized value estimated from the temperature gradient in the solution and the growth rate. In_xGa_<1- … More x>As single crystals with x values up to 0.12 were grown on GaAs seed by Rotational Bridgman method. The x values of the grown crystals are found to be homogeneous due to the feeding of GaAs source materials continuously into the In-Ga-As solution.3.Bridge layer growth technique has been successfully employed to realize high quality epitaxial layers of In_xGa_<1-x>As on patterned III-V binary substrates. For the growth of In_xGa_<1-x>As epilayers with high indium composition, a novel technique named as "composition conversion" has been successfully utilized. High quality epilayers have been grown with indium composition as high as 80%. Furthermore, the origins of the conversion mechanism have been studied in detail.4.Two selective growth techniques have been developed for the first time to grow In_xGa_<1-x>Sb and In_xGa_<1-x>As pyramidal epilayers with low etch pit density on III-V substrates viz., hollow pyramidal epitaxy technique, and the combination of composition conversion and hollow pyramidal epitaxy technique. In order to make use of the pyramidal epilayer for fabrication of optical devices, the effect of Te impurity on the structural properties of GaSb pyramidal epilayer has been studied in detail.5.p-type GaSb epilayers have been grown on n-type GaSb substrates by Zn diffusion technique. The composition profiles of the epilayers were obtained under various annealing conditions. Less