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Research on electronic states in a metallic quantum dot

金属量子点电子态研究

基本信息

批准号：
15204027
负责人：
OOTUKA Youiti
金额：
$ 31.95万
依托单位：
University of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15204027/
关键词：
metal fine particle discrete energy level tunnel spectroscopy STM quantum dot nano-electrodes cluster 原子ポイントコンタクト久保効果

项目摘要

We approached the research from three directions ; (1) investigation of 1-nm-scale metal cluster using a low-temperature STM, (2) investigation of 10-nm-scale metal particle made by electron-beam lithography, and (3) the development of nano-fabrication technique, and obtained the following results.1. We have obtained metal clusters coupled to a metal substrate via homogeneous tunnel barrier in three systems : Au cluster/the monomolecular film/Au(111) system, Au cluster/the dithiol thiol mixed molecular film/Au(111) system, and metal cluster/Al_2O_3 thin film /NiAl(110) system. Using them, we performed tunneling spectroscopy for many clusters systematically. The analysis of the I-V curves showed that the distribution of the offset charge, which is concentrated around zero, spreads with increase of the cluster size, and the non-neutral clusters appear when the size exceeds a certain value.2. We observed the discrete single-electron energy levels in a 10nm-Al particle using the fixed-electrode samples fabricated by electron-beam lithography. Distribution of level spacing was consistent, with the Wigner distribution.3. Other than direct EB lithography, angled-deposition method, mechanical break junction method, electro-chemical method and inorganic resist method were examined to make nano-gap electrodes. Fabrication process of SET made of 10nm gold colloidal particle was established and the transistor operation was verified. Using the break junction method, the number of conduction channels and their transmission coefficients were determined for superconducting Al atomic point contacts., and the current-phase relationship was determined.4. We also obtained several new findings in mesoscopic metal particles. They include the discovery of new vortex states in mesoscopic superconductors, the mechanism of TMR enhancement in ferromagnetic SETs, and the pressure effect of SET.

我们从三个方向进行了研究：（1）利用低温STM研究1-nm尺度的金属团簇;（2）利用电子束光刻技术研究10-nm尺度的金属颗粒;（3）纳米加工技术的发展，取得了以下成果.我们在三个体系中获得了通过均匀隧道势垒耦合到金属衬底上的金属团簇：Au团簇/单分子膜/Au（111）体系，Au团簇/二巯基硫醇混合分子膜/Au（111）体系和金属团簇/Al_2O_3薄膜/NiAl（110）体系。利用它们，我们对许多团簇进行了系统的隧道光谱研究。对I-V曲线的分析表明，随着团簇尺寸的增大，偏置电荷的分布逐渐扩展，偏置电荷主要集中在零附近，当团簇尺寸超过一定值时，出现非中性团簇.利用电子束光刻技术制备的固定电极样品，观察到了10 nm铝粒子中的分立单电子能级。能级间距的分布符合维格纳分布.除直接电子束光刻法外，本文还研究了倾斜沉积法、机械断裂结法、电化学法和无机抗蚀剂法制备纳米间隙电极。建立了10 nm金胶体粒子的单电子晶体管的制作工艺，并验证了晶体管的工作特性。用断裂结法测定了超导铝原子点接触的导电沟道数及其传输系数。并确定了电流-相位关系.在介观金属粒子方面，我们也获得了一些新的发现。它们包括介观超导体中新涡旋态的发现，铁磁SET中TMR增强的机制，以及SET的压力效应。