New Transport Phenomena from Communication of Multiple Edge Channels

w：\awards\awards96\num.doc 9700767 Gwinn该实验研究项目的重点是由量子霍尔效应（QHE）中准二维电子气周边附近的“边缘态”形成的导电系统。对于将多个边缘状态带入通信的样本几何形状，预测了从根本上新的传输行为。两个样品的几何形状将在这个项目中使用。这些是GaAs/AlGaAs超晶格柱，其边缘状态在2D表面鞘层上通信;以及栅极GaAs/AlGaAs异质结，其边缘状态跨越长而窄的“线栅极”势垒通信。现有的理论预测，在这些情况下，将进行测试与测量，使用高场（19特斯拉），低温（20 mK）的装置从MBE生长的GaAs/AlGaAs异质结构制造的样品。预计这些结果将促进对准一维和各向异性三维材料中电子输运的一般理解。本实验研究项目探讨基于微电子学中最先进的器件技术之一的新型器件中的电子输运行为;该器件基于GaAs- GaAlAs系统。这种系统被用在一些先进的电子设备的计算机使用，因为它可以导致更快的操作比等效器件的硅。实验将基于在GaAlAs技术中制造的薄导电层，该技术提供了受限的二维“电子气”，其中来自杂质和缺陷的残余散射降低到极低的水平，从而可以观察到在非常低的温度和高磁场下的固有电子气行为，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，这些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性质，涉及研究生谁将得到良好的培训，进入行业，政府或教育职位。***

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. ***