Light-Emitting Devices with Self-Formation Disordered Quantum Dots

制备了SiGe材料体系的无序超晶格，研究了无序超晶格对间接跃迁半导体发光性能的增强作用。在无序超晶格中，各层的厚度是随机变化的。随着组分比x的增大，发光增强程度增大，当x&lt;0.55时，Si^ Ge^x/Si的发光增强幅度最大可达50倍<1-x>。在Si衬底和生长层之间插入SiGe合金缓冲层进一步增强了发光，生长了GaAs间隔层厚度逐渐变化的（InAs/GaAs）叠层，以寻找最佳间隔层厚度。通过TEM观察确定：在h和2 h之间。这里h是InAs量子点的高度。低于h的点被拆除，超过2 h的点不堆叠。在GaP衬底上原位生长了InP量子点，并在GaP衬底上生长了InP量子点， ...更多信息 e的AlP衬底上，这是很难获得的。这些点几乎没有形成，它们的尺寸往往很大：通过将生长温度降低到420 ℃，我们成功地形成了尺寸为25- 40 nm的点。在我们的生长实验中，发现InN和GaN没有成为均匀的固溶体，通过提高生长温度可以抑制InN的偏析，但是生长速度变得非常低。我们的等离子体激发生长方法可以在较低的温度下生长出均匀的InGaN，而分离的InN可以用来形成量子点，只要它们的尺寸足够小，可以表现出量子效应。InN量子点形成的最佳条件是未来的研究课题，这些基础性的实验成果对于实现量子结构半导体发光器件的高效率具有重要意义。详细内容发表在7篇科技期刊论文和2篇口头报告中。少

The disordered superlattices of SiGe material system were fabricated to investigate the enhancement of luminescence capability of an indirect transition semiconductors. In a disordered superlattices, individual thicknesses of layers are randomly variated. The luminescence enhancement becomes greater with increasing the composition rate x and at most 50 times in x<0.55 of Si^<1-x>Ge^x/Si. The insertion of SiGe alloy buffer layer between Si substrate and a grown layer enhances the luminescence further.The stacked (lnAs/GaAs)-layers in which the thicknesses of GaAs spacers were gradually varied were grown to find an optimum spacer thickness. It was determined by the TEM observations : between h and 2h. Here h is the the height of InAs quantum dots. Below h the dots were demolished and beyond 2h the dots were not stacked. The investigations of luminescence enhancement by the stacked layers will be entered into details.The self-formed InP quantum dots on the GaP substrate were grown in plac … More e of on the AlP substrate which is difficult to obtain. The dots are hardly formed and their sizes tend to be large : 400-500nm at a conventional growth temperature 550ﾟC.We succeeded to form the dots of 25-4Onm in size by decreasing the growth temperature to 420ﾟC.In our growth experiments, it was found that InN and GaN do not become a uniform solid solution, but InN is segregated in GaN.The segregation can be suppressed by increasing the growth temperature, but the growth rate becomes extremely low. Our plasma-excited growth method can grow a uniform InGaN at lower temperature.The segregated InN would be utilized for the quantum dot formation, provided their sizes are small enough to exhibit quantum effects. Optimum conditions for the quantum dots formation of InN are future subjects.These fundamental experimental achievements are worthwhile to actualize a high efficiency of light-emitting devices by quantum structured semiconductors. Details were published in 7 papers of scientific journal and 2 oral presentaions. Less