Construction of wide gap semiconductor nano-Quantum Dots

宽禁带半导体纳米量子点的构建

基本信息

批准号：
10305001
负责人：
YAO Takafumi
金额：
$ 24.64万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

项目摘要

The ultimate goal of this research is to establish the fundamental materials technology for the short-wavelength optoelectronics. To this end, we have set the following research objectives : (1) development of widegap II-VI compound semiconductors which have bandgaps ranging from the visible to uv wavelength region ; (2) development of self-organizing growth processes for those semiconductors to fabricate qunantum dots with a nano-meter size. The materials system to be investigated includes a ZnO-based materials system, ZnSe/ZnSe-based heterostructure system, and ZnCdSe/ZnSe-based heterostructure system. We have selected those material systems because of the following reasons : (1) They can cover the wavelength region from the visible to uv range ; (2) The exciton binding energies of ZnO and ZnSe/ZnSe quantum wells have large binding energies of 60 meV and 40 meV, respectively, which are much larger than the thermal energy at room temperature thereby making excitons survive at room tem … More perature or even at higher temperatures ; (3) We have been extensively working on blue-green light emitting devices of ZnCdSe/ZnSe heterostructures. I would like to mention that we have already established MBE techniques to grow those II-VI compounds, which is quite essential to lead the research project to a success.The achievements obtained in this research project can be summarized as follows : (1) We have established the molecular beam epitaxy technique for the growth high-quality widegap II-VI compound semiconductors. In addition to the already established MBE growth techniques for ZnSe, ZnSe, and ZnCdSe, we have developed (a) the oxygen-plasma assisted MBE growth technique for the growth of high-quality ZnO-based materials, (b) the fabrication techniques for heterostructures of ZnSe/ZnS, ZnCdSe/ZnSe, and ZnMgO/ZnO, and (c) the technique to control the lattice polarity of ZnO layers. Those techniques are crucial to the fabrication of well-controlled nano-scale semiconductor quantum dots. (2) We have established the self-organized fabrication processes for ZnO quantum pyramids, ZnSe/ZnS nano-scale quantum dots, and ZnCdSe/ZnSe nano-scale quantum dots. In particluar, the fabrication of ZnO quantum pyramids are the first achievements in oxide semiconductors. (3) We have discovered various novel optical properties unique to those material systems and nano-scale quantum dots. In particular, (a) The effects of localization in ZnCdSe/ZnSe quantum dots on optical properties have been elucidated, which can be utilized to enhance emisison probabilities thereby leading to the fabrication to high-bright light emitting devices. (b) The realization of induced emission from ZnO and ZnO/ZnMgO quantum structures based on excitonic mechanisms, which may open up a excitonic optical devices. (c) The first observation of spectral diffusion in ZnCdSe/ZnSe quantum dots, which may be utilized to fabricate novel optical memory devices. We hope that those achievements will contribute to the establishment of short-wavelength optoelectronics. Less

本研究的最终目标是建立短波长光电子学的基础材料技术为此，我们设定了以下研究目标：（1）开发具有从可见光到带隙的宽禁带II-VI化合物半导体。 (2) 开发用于制造纳米尺寸量子点的半导体自组织生长工艺。要研究的材料系统包括ZnO基材料系统， ZnSe/ZnSe基异质结构系统和ZnCdSe/ZnSe基异质结构系统我们选择这些材料系统的原因如下：（1）它们可以覆盖从可见光到紫外范围的波长区域；（2）激子。 ZnO和ZnSe/ZnSe量子阱的结合能很大，因此结合能分别为60meV和40meV，远大于室温下使激子存活的热能在室温甚至更高温度下；（3）我们一直在广泛研究 ZnCdSe/ZnSe 异质结构的蓝绿光发射器件，我想提一下，我们已经建立了 MBE 技术来生长这些 II- VI化合物，这对于该研究项目的成功至关重要。本研究项目取得的成果可概括如下：（1）建立了生长高质量宽禁带II-VI化合物的分子束外延技术除了已经建立的 ZnSe、ZnSe 和 ZnCdSe 的 MBE 生长技术之外，我们还开发了 (a) 用于生长高质量 ZnO 基材料的氧等离子体辅助 MBE 生长技术，(b) ZnSe/ZnS、ZnCdSe/ZnSe 和 ZnMgO/ZnO 异质结构的制造技术，以及 (c) 控制晶格极性的技术这些技术对于制造良好控制的纳米级半导体量子点至关重要（2）我们已经建立了 ZnO 量子金字塔、ZnSe/ZnS 纳米级量子点和 ZnCdSe/ 的自组织制造工艺。特别是 ZnSe 纳米级量子点的制备，是氧化物半导体领域的首次成就。 (3) 我们发现了各种独特的新颖光学特性。特别是，(a) ZnCdSe/ZnSe 量子点的局域化对光学性质的影响已被阐明，可用于提高发射概率，从而实现高发射率的制造。 (b)基于激子机制实现ZnO和ZnO/ZnMgO量子结构的诱导发射，这可能开辟激子光学领域。 (c) 首次观察到 ZnCdSe/ZnSe 量子点的光谱扩散，我们希望这些成果将有助于短波长光电子学的建立。