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Fabrication and Optical Characterization of Assembled Semiconductor Nanocrystals

组装半导体纳米晶体的制造和光学表征

基本信息

批准号：
11440095
负责人：
KANEMITSU Yoshihiko
金额：
$ 3.78万
依托单位：
NARA INSTITUTE OF SCIENCE AND TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

We have fabricated assembled semiconductor nanocrystals by ion-implantation, colloid, and vacuum-deposition techniques and studied their optical properties. The a-Si/SiO_2 multilayer structures on (001) Si substrates were formed by an electron beam deposition technique. The size dependence of the luminescence spectrum and lifetime showed that high-quality two-dimensional a-Si layers were formed between SiO_2 layers. After thermal annealing of a-Si/SiO_2 multilayers, arranged Si nanocrystals were formed between SiO_2 layers and the size of Si nanocrystals were determined by the thickness of the a-Si layer. The Ge nanocrystals samples were synthesized by multi-energy or low-energy ion-implantation techniques. This multi-energy ion implantation gave a uniform Ge concentration profile in SiO_2 glasses. The transmission electron microscopy (TEM) observations showed that the size fluctuation of Ge nanocrystals was very small. In addition, the low-energy ion implantation produced Ge nanocrystal in the very narrow region in SiO_2 matrices. The TEM observation showed that the Ge nanocrystals were lined up near the surface. The size fluctuation of nanocrystals in this work is much smaller than that of prepared by conventional ion-implantation and rf co-sputtering techniques. Moreover, we have developed new fabrication methods of compound semiconductor nanocrystals in SiO_2 or Al_2O_3 films by sequential ion implantation. ZnS and CdS nanocrystals in Al_2O_3 matrices were faced and aligned with the Al_2O_3 lattice. In GaAs, ZnS, and CdS nanocrystals, efficient photoluminescence due to free excitons appeared near the absorption edge. Spectroscopic analysis showed that high-quality compound semiconductor nanocrystals were formed by sequential ion implantation techniques. It is demonstrated that ion implantation synthesis is one of the most versatile methods for the fabrication of assembled semiconductor nanocrystals.

我们采用离子注入、胶体沉积和真空沉积技术制备了组装的半导体纳米晶，并研究了它们的光学性质。采用电子束沉积技术在（001）Si衬底上制备了a-Si/SiO_2多层膜结构。发光光谱和寿命的尺寸依赖性表明，高质量的二维a-Si层之间的SiO_2层形成。a-Si/SiO_2多层膜经热退火后，在SiO_2层间形成了有序排列的Si纳米晶，其尺寸由a-Si层的厚度决定。采用多能或低能离子注入技术合成了Ge纳米晶样品。这种多能离子注入在SiO_2玻璃中获得了均匀的Ge浓度分布。透射电子显微镜（TEM）观察表明，Ge纳米晶的尺寸波动很小。另外，低能离子注入在SiO_2基体中产生了很窄的Ge掺杂区。透射电镜观察表明，Ge纳米晶在表面附近排列整齐。与传统的离子注入和射频共溅射技术相比，本工作中制备的纳米晶的尺寸波动要小得多。此外，我们还发展了在SiO_2或Al_2O_3薄膜中用顺序离子注入法制备化合物半导体纳米晶的新方法。ZnS和CdS纳米晶在Al_2O_3基体中与Al_2O_3晶格相对排列。在GaAs，ZnS和CdS纳米晶体中，由于自由激子的有效的光致发光出现在吸收边附近。光谱分析表明，通过顺序离子注入技术，形成了高质量的化合物半导体纳米晶体。离子注入法是制备半导体纳米晶组装体的最常用方法之一。