Fabrication of quantum dots with visible light emission and study of its stimulated emission

量子点和量子线中特殊类型的态密度有望改善半导体激光器的性能。目前这方面的研究主要集中在红外InGaAS系统上。然而，为了实现高密度光信息处理和存储等应用，以及提高硅光电探测器的吸收系数，在光电集成电路中采用小型集成光子器件，需要高性能、高效率的可见光特别是短波长的半导体激光器。量子点中的激子和激子分子具有较大的振子强度或较大的光学增益。因此，如果用具有大激子结合能的宽禁带半导体制备这种情况，实现这种高性能短波激光器的可能性将很大。本课题研究了CdSe、ZnSe、CdS宽b…More和gap半导体量子点。研究了CdSe量子点奥斯特瓦尔德成熟引起的不稳定性、ZnSe和CdS量子点较高的稳定性、量子约束效应引起的ZnSe量子点光发射的蓝移、CdS/ZnSe异质结构中II型能带排列的研究、CdS量子点纵向光学声子发射过程中能量守恒在能量弛豫过程中的作用。研究还表明，CdS/ZnMgCdS异质结构为I型，这将被证明是具有更高发光效率的有效方法。为了实现量子点与光场之间的强耦合，发展了AFM纳米光刻技术，可以制作周期为100nm的量子点阵列。基于这些结构的受激辐射目前正在研究中，但掺杂GaN的受激辐射是在紫外波长区域观察到的。少

The special type of the density of states in quantum dots and wires are expected to have the capability to improve the performance of semiconductor lasers. The researches toward this direction are now mainly promoted on the infrared InGaAS systems. However for the applications such as the high-density optical information processing and storage and also for increasing the absorption coefficient of Silicon photodetectors to have small integrated photonic devices in optoelectronic integrated circuits, visible and especially short wavelength semiconductor lasers with high performance and high efficiency are necessary. Excitons and excitonic molecules confined in quantum dots are predicted to have the large oscillator strength or large optical gain. Therefore if such a situation is prepared with wide bandgap semiconductors with their large exciton binding energies, the possibility to realize such a high-performance short wavelength lasers will be high.In this project, CdSe, ZnSe, CdS wide b … More andgapsemiconductor quantum dots were studied. The instability due to the Ostwald ripening in CdSe dots, much higher stability in ZnSe and CdS quantum dots, the blue shift of the light emission in ZnSe quantum dots due to the quantum confinement effect, the study of the type II band lineup in CdS/ZnSe heterostructures, the role of the energy conservation in the energy relaxation processes in the CdS quantum dots during the longitudinal optical phonon emission were studied. It was also shown that CdS/ZnMgCdS heterostructures are type I and this will prove to be effective to have the higher luminescence efficiency. For the purpose of realizing the strong coupling between the quantum dots and the optical field, AFM nanolithography was developed and the fabrication of quantum dot array with the period of 100nm could be fabricated. The stimulated emission based on these structures are now under study, but the stimulated emission in doped GaN was observed in the ultra-violet wavelength region. Less