Localization in Semiconductor Heterostructures Studied by Subsurface Charge Accumulation Imaging

9970756 tessmer本项目采用一种新颖的技术——地下电荷积累成像（SCAI）来探测二维电子系统（2DES）的局部电子结构。SCAI是一种扫描探针方法，允许在低温环境中局部解析微量电荷。最初的实验检查了大量2DES充当电导体的样品。相比之下，通过将SCAI应用于绝缘状态下的2DESs，就可以探索出完全不同的物理特性。这将包括无序主导绝缘体中的2DES，以及固定的维格纳晶体体系，以及量子霍尔平台中心的内部可压缩性。当前项目的重点是开发这样一种能力。这将需要更先进的样品几何形状，其中包括通过隧道势垒与2DES分离的三维电极。具体目标是演示SCAI对这些系统的效用。本研究应用新的扫描探针显微技术来探测半导体系统中局限于二维空间的电子行为。我们的目标是进一步发展这项技术，使我们能够绘制出样品处于绝缘状态时电荷形成的空间模式。这将使我们能够研究电子相互作用的基本方面和半导体的无序性。这项研究为一项新兴技术的研究生和博士后研究人员提供了一个具有挑战性的培训场所

9970756TessmerThis project applies a novel technique, subsurface charge accumulation imaging (SCAI), to probe the local electronic structure of two-dimensional electron systems (2DES). SCAI is a scanned probe method that permits minute amounts of electrical charge to be locally resolved in a cryogenic environment. Initial experiments have examined samples for which the bulk of the 2DES acted as an electrical conductor. In contrast, by applying SCAI to 2DESs in an insulating state with respect to bulk transport, fundamentally distinct physics may be explored. This would include 2DES in the disorder-dominated insulator, and pinned Wigner crystal regimes, in addition to the interior compressibility at the center of a quantum Hall plateau. The focus of the current project is to develop such a capability. This will require more advanced sample geometries, which include a three-dimensional electrode separated from the 2DES by a tunneling barrier. The specific goal is to demonstrate the utility of the SCAI for these systems.%%%This research applies new scanning probe microscopy techniques to probe the behavior of electrons confined to two dimensions in semiconductor systems. The goal is to further develop the technique to allow us to map out the spatial patterns formed by the charge when the sample is in an insulating state. This will permit us to investigate fundamental aspects of the electron interactions with each other and with the disorder of the semiconductor. The research provides a challenging training ground for graduate students and postdoctoral research associates in an emerging technology.***