Fabrication of Semiconductor Nanostructured New Materials and Applications to Functional Devices

1.纳米结构Ge和Si新材料的制备与表征本课题组利用团簇束蒸发技术成功地制备出了尺寸均匀的Ge和Si团簇。通过高分辨透射电子显微镜、X射线光电子能谱等技术研究发现，在80 kbar的高压下，这些团簇的晶体结构转变为它们的高压相，如ST-12（Ge）和BC-8（Si）。结果发现，只有当样品在高压下保持很长一段时间（10天）时，才发生从金刚石到ST-12的相变。此外，体锗中的高压形式是亚稳定的，与ST-12结构在高达700 ℃下稳定的纳米结构形成鲜明对比。SiO_x纳米结构在ULSI低介电常数材料中的应用气相蒸发法制备的SiO_x纳米结构薄膜具有很低的介电常数（小于1.9）。这意味着这种材料是未来ULSI层间绝缘材料的优秀候选者。本发明申请了专利。多层掺硅玻璃膜光学谐振腔的研制提出了一种新的多层膜光学谐振腔的制备方法。多层膜是在薄膜沉积过程中通过溅射的射频功率调制形成的。利用多层膜和金属反射镜组成的法布里-珀罗谐振腔，从镶嵌在SiO_2玻璃中的纳米Si颗粒的宽可见光发射中获得了相对窄的光谱。

1. Fabrication and Characterization of Nanostructured Ge and Si New MaterialsThe cluster-beam evaporation technique developed by our group was succesfully utilized to fabricate Ge and Si clusters with excellent size uniformity. Surprisingly, the crystal structures of those clusters have been transformed to their high pressure phases such as ST-12(Ge) and BC-8(Si) : The new structures were investigated by various techniques including the high resolution transmission electron microscopy, x-ray photo-elctron spectroscopy, etc.A high pressure up to 80kbar was applied to crystalline Ge flakes to form the bulk ST-12 structure. It was found that the phase transformation from the diamond to ST-12 occurs only when the specimen is kept at the high pressure for a long period (ten days). Furthermore, the high pressure form in bulk Ge was meta-stable, showing a striking contrast to the nanostructures in which the ST-12 structure is stable in up to 700ﾟC.2. Application of SiO_x Nanostructures to A Low Dielectric Constant Material in ULSISiO_x Nanostructured films fabricated by the gas-evaporation technique shows a very low dielectric constant(less than 1.9). This means that this material is an excellent candidate for the future interlayer insulating material for ULSI.A patent was applied to this invension.3. Fabrication of Optical Resonator Composed of Multi-Layered Si-Doped Glass FilmsA new fabrication method was developed to form a multi-layered optical mirror with high reflectivity. The multi-layer was formed by the rf-power modulation of the sputtering during the film deposition. Relatively narrow spectra were obtained from a broad visible light emission from Si nano-particles embedded in the SiO_2 glass, using a Fabri-Perot resonator composed of the multi-layer and metal reflectors.