Fundamental and Technological Basis of Compliant Universal Substrates for Growing Defect Free Heteroepitaxial Films

提出的研究和教育计划的目标是：(1)开发一种可行的顺应性衬底技术，该技术可用于生长大(15%)晶格失配和不同晶格结构的无缺陷异质外延材料，以及(2)了解顺应性衬底的基本物理，并建立一个物理模型来定量描述衬底顺应性现象。简而言之，该计划旨在建立符合通用基板的理论和技术。作为这项研究的结果，一种或两种类型的衬底，可能是GaAs或Si，将足以容纳各种化合物半导体外延材料，包括那些没有合适的常规衬底进行生长的材料。建议的柔顺通用衬底基本上是由超薄(10A到100A)单晶(例如，GaAs或Si)结合到具有大(10度)扭转角的GaAs或Si大块晶体上制成的。认为扭转晶界的微观结构和极薄的粘结层对异质外延覆盖层的结构顺应性起着至关重要的作用。我们认为，双晶体的扭转结合的薄部分的行为有点类似于自由站立的薄模板，以实现其顺应性。我们的初步实验结果表明，InGaP、GaSb和InSb分别与GaAs有1%、8%和15%的失配，可以在兼容的通用衬底上无缺陷地生长。这一建议汇集了Lo和Sass的专业知识，Lo开发了顺应性通用衬底的概念，Sass对双晶中包含的晶界结构进行了广泛的研究，这些双晶具有与顺应性通用衬底相同的几何形状。由Lo、Sass、3名博士生和至少4名本科生组成的研究团队将执行三项任务：基础材料研究、顺应性衬底技术开发以及材料和器件演示。通过这些努力，顺应性通用基板的物理机制、技术和应用有望得到建立。几十年来，对于从事半导体材料和器件工作的人来说，符合标准的通用基板一直是他们的梦想。兼容通用衬底的实现将消除半导体研究中最严重的障碍之一，并显著推动微电子、光电子以及两者的集成技术。拟议的研究将大大有助于实现这一目标。

The objectives of the proposed research and education program are: (1) to develop a viable technology for compliant substrates which can be used to grow defect-free heteroepitaxial materials of large (15%) lattice mismatches and different lattice structures, and (2) to understand the underlining physics of compliant substrates and to establish a physical model to quantitatively describe the phenomenon of substrate compliance. In brief, this program aims to establish the theory and technology of compliant universal substrates. As a result of this research, one or two types of substrates, perhaps GaAs or Si, will be sufficient to accommodate a large variety of compound semiconductor epitaxial materials, including those having no proper conventional substrates on which to grow. The proposed compliant universal substrate is essentially made of an ultra thin (10 A to 100A) single crystal (e.g. GaAs or Si) bonded to a GaAs or Si bulk crystal with a large ( 10 degrees) twist angle. It is believed that the microstructure of the twist boundary and the extremely thin bonded layer play a critical role in making the structure compliant to the heteroepitaxial overlayer. We conceive that the twist bonded thin portion of the bicrystal behaves somewhat similar to a free standing thin template to achieve its compliance. Our preliminary experimental results show that InGaP, GaSb, and InSb, with 1%, 8%, and 15% mismatch to GaAs, respectively, can be grown defect-free on the compliant universal substrates. This proposal brings together the expertise of Lo, who has developed the concept of the compliant universal substrate, and of Sass, who has carried out extensive studies of the structure of grain boundaries contained in bicrystals with the same geometry as in the compliant universal substrate. The research team made of Lo, Sass, 3 Ph.D. students and at least 4 undergraduates will perform three tasks: fundamental materials research, compliant substrate technology development, and material and device demonstrations. Through these efforts, the physical mechanisms, technologies, and applications of compliant universal substrates are anticipated to be established. Compliant universal substrates have been a dream for many decades for people working on semiconductor materials and devices. The realization of compliant universal substrates will remove one of the most serious road blocks in semiconductor research and significantly advance the technologies of microelectronics, optoelectronics, and the integration of both. The proposed research will contribute substantially to achieving this goal.