New Transport Phenomena from Communication of Multiple Edge Channels

Gwinn这个实验研究项目的重点是由量子霍尔效应（QHE）中靠近准二维电子气体周长的“边缘态”形成的导电系统。从根本上说，新的传输行为预测了样本几何，将多个边缘状态带入通信。本项目将使用两个几何样例。这些是GaAs/AlGaAs超晶格柱，其边缘状态在二维表面护套上通信；以及一个门控GaAs/AlGaAs异质结，其边缘态通过长而窄的“线栅”势垒进行通信。在这些情况下，现有的理论预测将通过使用高场（19Tesla），低温（20mK）设备对由MBE生长的GaAs/AlGaAs异质结构制成的样品进行测量来验证。期望这一结果将促进对准一维和各向异性三维材料中的电子输运的一般理解。该实验研究项目基于微电子领域最先进的器件技术之一，探索新型器件中的电子传输行为；基于GaAs- GaAlAs系统。这种系统被用于一些先进的计算机电子设备中，因为它比同等的硅制设备运行得更快。实验将基于GaAlAs技术制造的薄导电层，它提供了一个受限的二维“电子气体”，其中杂质和缺陷的残余散射减少到极低的水平，因此可以观察到在极低温度和高磁场下固有的电子气体行为，并与最近的理论模型进行比较。这项研究的结果可能包括不寻常的新效果或材料，可能会在技术上找到新的应用。这个研究项目是跨学科的，涉及研究生，他们将接受良好的培训，进入工业、政府或教育部门。＊＊＊

w:\awards\awards96\num.doc 9700767 Gwinn This experimental research project focuses on conducting systems formed by the "edge states" that lie near the perimeter of quasi- two dimensional electron gases in the quantum Hall effect (QHE). Fundamentally new transport behavior is predicted for sample geometries that bring multiple edge states into communication. Two sample geometries will employed in this project. These are a GaAs/AlGaAs superlattice pillar with edge states communicating on a 2D surface sheath; and a gated GaAs/AlGaAs heterojunction with edge states communicating across a long, narrow "line gate" barrier. Existing theoretical predictions in these cases will be tested with measurements to be made using a high-field (19Tesla), low temperature (20mK) apparatus on samples fabricated from MBE- grown GaAs/AlGaAs heterostructures. It is expected that the results will advance general understanding of electronic transport in quasi-1D- and in anisotropic 3D- materials. %%% This experimental research project probes electron transport behavior in novel devices based on one of the most advanced device technologies in microelectronics; that based on the GaAs- GaAlAs system. This system is used in some advanced electron devices for computer use because it can lead to faster operation than equivalent devices made of silicon. The experiments will be based on thin conducting layers fabricated in the GaAlAs technology which give a confined two-dimensional "electron gas" in which the residual scattering from impurities and imperfections is reduced to extremely low levels, so that inherent electron gas behavior at very low temperatures and at high magnetic fields can be observed, and compared to recent theoretical models. Results from this research may include unusual new effects or materials which may find new application in tech nology. This research project is interdisciplinary in nature and involves graduate students who will be excellently trained to enter positions in industry, government or education. ***