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Field Emission from two dimensional electrons at a hetero-interface of superlattice and application to picosecond pulse electron source

超晶格异质界面二维电子场发射及其在皮秒脉冲电子源中的应用

基本信息

批准号：
10450017
负责人：
0KANO Tatsuo
金额：
$ 8.45万
依托单位：
University of Tokyo
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 1999
项目状态：
已结题

项目摘要

Field emission property of two dimensional electron gas at a GaAs/GaAlAs heterointerface was studied. The aim of the research is to elucidate the tunneling phenomena of two-dimensional electron gas through a surface potential barrier perpendicular to the heterointerface. The two-dimensional electron gas localized in a accumulation layer of GaAs is featured by its high mobility and coherence. The measurement of energy distribution and time response of emitted electrons together with the observation of field emission pattern is a target of this experimental study.Fabrication of atomically-clean apex structure at a corner of the GaAs wafer with superlattice structures was an important experimental technique in the research program. We have developed a cleavage mechanism compatible with ultrahigh vacuum environment. Cleavage along <011> and <011> direction on a (100) plane of a GaAs wafer makes a sharp edge with an apex angle of90o. The curvature radius of the apex was less than 10nm, which is small enough to keep high field strength at the surface. We have observed a planer emission pattern from the apex. For the measurement of energy distribution and time response after photo excitation by a picosecond pulse laser, we have also developed a hemispherical electrostatic analyzer with energy resolution of 20 meV and a streak-camera system which has high sensitivity for single electron detection with time resolution of 50ps. By utilizing these newly developed devices, we are going to measure the energy distribution and the time response of the emitted electrons.

研究了GaAs/GaAlAs异质界面二维电子气的场发射特性。研究的目的是阐明二维电子气通过垂直于异质界面的表面势垒的隧穿现象。局域在GaAs积累层中的二维电子气具有高迁移率和相干性的特点。测量发射电子的能量分布和时间响应以及观察场发射图形是本实验研究的目标，在具有超晶格结构的GaAs晶片的角部制备原子级清洁的顶点结构是本研究计划中的一项重要实验技术。我们发展了一种与真空环境相容的解理机制。GaAs<011><011>晶片在（100）面上沿沿着和方向解理形成顶角为90 °的锐边。顶点的曲率半径小于10 nm，这足够小以在表面处保持高场强。我们已经观察到一个平面发射模式从顶点。为了测量皮秒脉冲激光光激发后的能量分布和时间响应，我们还研制了能量分辨率为20 meV的半球形静电分析器和时间分辨率为50 ps的高灵敏度单电子探测条纹相机系统。利用这些新开发的装置，我们将测量发射电子的能量分布和时间响应。