Basic Research of Ultra-Fine-Structure Fluoride/Si Light Emitting Device with Si Substrate

本项目是实现以硅为衬底的超精细结构氟化物/硅发光器件的基础性研究，该器件通常被认为很难应用于光电子集成电路（OEIC）。主要目的是实现氟化物（CaF_2）和Si的单晶超晶格或超细周期结构，通过分析能带图，建立这种超晶格的材料性质理论，为这种超晶格在光学器件中的应用提供基础知识。主要研究结果如下：用离子化团簇束外延（ICBE）生长氟化物（CaF_2）-Si超晶格和超薄层。明确了在Si（111）层上外延生长CaF_2薄层（~ nm）和在CaF_2上外延生长Si层的条件。从热力学上讲，由于各材料表面能的差异太大，Si在CaF_2上容易团聚 关于我们 大.为了克服这个问题，我们研究了在相对较低的衬底温度600 μ C下的电离和加速（V_a=2KV）的生长过程。结果得到50对5 nm-CaF_2/5 nm-Si超晶格，用原位反射高能电子衍射（RHEED）和扫描电镜（SEM）观察了CaF_2/SiO_2复合材料的电子能带结构，并对CaF_2/SiO_2复合材料的电子能带结构进行了理论分析为了建立CaF_2/Si超细周期结构光学性质的理论基础，本文采用紧束缚方法对CaF_2/Si超晶格进行了研究。计算结果表明，随着Si层厚度的减小，CaF_2/Si（100）超晶格的光学跃迁性质接近于直接跃迁，并且由于深绝缘体势垒威尔斯阱对电子的限制，电子能级将发生显著的量子化。我们获得了超精细结构氟化物/Si发光器件的可能性和实现这些器件所必需的基本知识。少

This project is a basic research for realization of ultra-fine-structure fluoride/Si light emitting device featured by using silicon substrate, which has usually been considered to by very difficult to apply to opto-electronics integrated circuit (OEIC). The main purpose is realization of single-crystalline superlattice or ultra-fine periodic structures with fluoride (CaF_2) and Si, establishment of the theory on material properties of this superlattice by analyzing energy band diagram in order to obtain basic knowledge on application of this superlattice to optical devices. Results obtained are summarized as follows.Crystal growth of fluoride (CaF_2) -Si superlattice and ultra-thin layers was investigated using ionized cluster beam epitaxy (ICBE). Condition of epitaxial growth of CaF_2 thin layers (-nm) on Si (111) layers, and Si layers on CaF_2 was made clear. Thermodynamically, Si tend to agglomerate on CaF_2 because the difference between the surface energy of each material is too … More large. To overcome this problem, we investigated the growth process at relatively low substrate temperature 600^ﾟ with ionization and acceleration (V_a=2KV). As a result, 50 pairs of 5nm-CaF_2/5nm-Si superlattice was obtained, which wafound to be single crystalline nature shown by in-situ reflection high energy electron diffraction (RHEED) and has relatively flat surface shown by SEM observation.Theoretical analysis was made for the electronic band structure of CaF_2/Si superlattice using tight binding method in order to establish the basis of the theory of optical properties of CaF_2/Si ultra-fine periodic structures. As a result of the calculation, it was found optical transition properties of the CaF_2/Si (100) superlattice approaches direct transition as the thickness of Si layer gets thinner, and that remarkable quantization of electron energy levels is expected due to electron confinement by deep insulator-barriered quantum wells.By these results, we obtained possibility of ultra-fine-structure fluoride/Si light emitting devices and basic knowledge essential to the realization of these devices. Less