New Quantum Optoelectronic Properties of Semiconductors with Disordered Structures

利用超高真空扫描隧道显微镜对具有无序结构的半导体的劈裂表面进行了形变观察。经过与厂家多次讨论，发明了不影响表面观察功能的改造方法。研究项目的持续进行成为可能。通过生长InAs/GaAs量子点的堆叠层来研究有序或无序组装的形成条件。由于间隔层的厚度影响到点耦合的强度，所以间隔层的厚度是变化的。通过高分辨率电子显微镜的观察，我们得到以下结果：(1)当间隔层厚度为点高度的1倍到2倍之间时，量子点相互耦合并有序组装；(2)当间隔层厚度小于点高度时，量子点被破坏；(3)当间隔层厚度大于点高度时，量子点不耦合并无序组装。InAs/GaAs量子点的堆叠层增加了发光强度的饱和度。通过实验发现了InGaN中pahse的分离。这种分离可以用于GaN矩阵中InN的点形成。缩小尺寸的问题留作将来讨论。现在研究了AIN层的生长，以观察等离子体激发对发光性能的影响。量子点是通过Stranski-Krastanov生长模型制造出来的，该模型在二维层的一定厚度（过渡厚度）处开始形成三维岛屿。在本研究中，考虑了岛屿和点的应变和表面能，导出了解析方程。理论结果与实验结果吻合较好。该方程可应用于其他异质外延体系。无序超晶格的一些性质，如电子迁移率等尚未被表征。当观察到低电子迁移率时，它表明电子因无序而局域化。上海技术物理研究所对其进行了表征。合作计划将继续进行。少

Remodeling has been requested to observe the cleaved surface of semiconductors with disordered structures by the ultra high vacuum scanning tunneling microscope. After several times of discussions with manufacturers, the remodeling which does not deteriorate the function of the surface observation was invented. It becomes possible to work continuously the research project.The stacked layrs of InAs/GaAs quantum dots were grown to investigate formation condigions for ordering or disordering assembling. The thickness of GaAs spacer is varied, since the spacer thickness affects to the strength of dot coupling. Through the observations of high resolution electron microscope, we obtain the following results : (1) quantum dots couple each other and assemble orderly if the spacer thickness is between single and twice much of the dot height, (2) they are destroyed if the spacer thickness is thinner than the dot height, (3) they do not couple and assemble disorderly if the spacer thickness is th … More icker than the dot height. The saturation in luminescence intensity is increased by the stacked layrs of InAs/GaAs quantum dots.The pahse separation in InGaN was experimentally discovered. This separation could be utilized for the dot formation of InN in GaN matrix. The size reduction is left as the future subject. The growth of the AIN layr is now investigated to see the effect of plasma exitation on the luminescence properties.Quantum dots have ben fabricated through the Stranski-Krastanov growth modein which three dimensional islands begin to be formed at the certain thickness of two dimensional layr : a transitional thickness. The analytical equation was derived in this study by taking the strain and the surface energy of the islands and the dots into account. The teoretical reults agree well with the experimental results. The equation can be applied to other heteroepitaxial systems.There are some properties of disordered superlattices which have not been characterized yet such as electron mobility. When the low electron mobility is observed, it indicates the localizations of electrons by disordering. Shanghai Institute of Technical Physics has offered to characterize it. The collaboration scheme will be continued. Less