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Optical second harmonic spectroscopy of the surface and interface electronic states

表面和界面电子态的光学二次谐波光谱

基本信息

批准号：
10440090
负责人：
MIZUTANI Goro
金额：
$ 9.92万
依托单位：
Japan Advanced 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：
1998
资助国家：
日本
起止时间：
1998 至 2001
项目状态：
已结题

项目摘要

The objective of this research project is to explore the surface and interface electronic levels within several electron volts of Fermi level and relate them to the driving forces of typical surface and interface phenomena. The target material systems are (1) catalyst, (2) nanostructured metals, and (3) semiconductor structures.(1) I have clarified that the surface band gap of photocatalyst TiO_2 has a larger gap energy than that of the bulk for (110) face. I have also found that the wavefunction of the electronic states of this surface varies drastically as a function of the energy. I have also found that the band gap shifts to the higher energy side when the material is catalytically activated by UV light. I have found a correlation between the catalytic activity of the Ziegler-Natta catalyst and the emergence of an edge vibrational mode of α-TiCl_3 granules at 224cm^<-1>.(2) I have found a resonance in SH intensity from Au films on glass or NaCl(100). Besides plasmon resonance, I have found resonances of the transitions between electronic levels of Au(111) and (100) surfaces. I succeeded in following the variation of the electronic states of this metal as its film grows.(3) I have found a new electronic resonance of Ge(111)/thermal oxide interface near 【planck's constant】ω=1.17eV. This resonance was not found for a native oxide interface. The SH intensity patterns as a function of the azimuthal angle are quite different between the thermal oxide and native oxide interface. This result suggests that the electronic states of the Ge interface is sensitive to the oxidation condition and offers a basic information for the semiconductor material physics using Ge and Si.

本研究计划的目的是探索费米能级几个电子伏范围内的表面和界面电子能级，并将它们与典型表面和界面现象的驱动力联系起来。靶材料系统是（1）催化剂，（2）纳米结构金属，和（3）半导体结构。(1)本文阐明了光催化剂TiO_2的表面带隙比体相（110）面的带隙能量大。我还发现，这个表面的电子态的波函数，作为能量的函数，变化很大。我还发现，当材料被紫外光催化激活时，带隙向高能侧移动。发现Ziegler-Natta催化剂的催化活性与α-TiCl_3颗粒在224 cm ~ 2处出现的边振动模式有关<-1>。(2)我发现玻璃或NaCl（100）上的Au膜的SH强度发生共振。除了等离子体共振外，还发现了Au（111）和（100）面电子能级间跃迁的共振。我成功地跟踪了这种金属在薄膜生长过程中电子态的变化。(3)在[普朗克常数]ω=1.17eV附近发现了Ge（111）/热氧化物界面的一个新的电子共振。这种共振没有发现原生氧化物界面。作为方位角的函数的SH强度图案在热氧化物和原生氧化物界面之间是相当不同的。这一结果表明Ge界面的电子态对氧化条件敏感，为Ge和Si的半导体材料物理提供了基础信息。