Basic research and application of interface tunneling - Development of low temperature UHV-BEEM-

在本项目中，我们研究了以下课题：(1)利用弹道电子发射显微镜（BEEM）测量界面局部区域的电子传输及其修正；(2)利用扫描隧道显微镜（STM）结合分子束外延（MBE）研究晶格错配的III-V异质半导体界面；(3)利用高分辨率电子能量损失谱（HREELS）和STM测量吸附富勒烯分子与衬底之间的电荷转移；(4)表面电位和局部功函数(5)通过探测x射线辐照产生的发射电流来研究元素解析型STM(6)利用飞行时间原子探针和三维原子探针研究纳米晶体的形成机理。在此基础上，讨论了各种界面上常见的原子相互作用、电子传递、电荷转移、扩散、应变等问题。在BEEM(1)的研究中，我们成功地通过注入具有适当能量的电子来可逆地改变局部区域的电子传输特性。这项工作在太比特高密度记录的应用中引起了广泛的关注，被《科学》杂志引用为今天的主题。我们还使用MBE-STM成功地拍摄了在SiC衬底上生长的GaN层的原子分辨STM图像(2)。由于氮化镓在蓝光发射器件中的应用，对其表面原子结构和晶体生长过程的研究具有重要的科学意义和工业意义。我们的作品被邀请在各种国际会议上发表演讲。

In this project, we have studied on the following subjects as are listed below; (1) measurements of electronic transmission at a local area of interfaces and its modification using ballistic electron emission microscope (BEEM) (2) a study on lattice-mismatched III-V hetero-semiconductor interfaces using scanning tunneling microscope (STM) combined with molecular beam epitaxy (MBE) (3) charge transfer between adsorbed fullerene molecules and substrate measured by high-resolution electron energy loss spectroscopy (HREELS) and STM (4) surface potential and local work function measurements using STM (5) an study of elementally analytical STM by detecting emitted current induced by X-ray irradiation (6) formation mechanism of nano-crystalline crystals with time-of-flight atom-probe and 3-dimensional atom probe. Based on those results, atomic interaction, electron transmission, charge transfer, diffusion, strain, and etc, which are common issues at various interfaces, have been discussed.In a study of BEEM (1), we have succeeded in modifying electron transmission properties of local area reversibly by injecting electrons with an appropriate energy. This work has attracted much attention in an application to Tera-bit high density recording, cited as a today's topics in a journal of Science. We also succeeded in taking atomically resolved STM images of GaN layer grown on SiC substrate using MBE-STM (2). Studies on atomic structure of surfaces and processes in crystal growth of GaN layer are quite important both scientifically and industrially because of its application to blue light emitting devices. Our works were presented as an invited talk at various international conferences.