Landolt-Börnstein - Group III Condensed Matter

2 Overview of systems


The discovery of the quantized conductance in ballistic quantum point contacts (QPCs) has both motivated as well as enabled a large number of subsequent experiments in the field of mesoscopic transport in low-dimensional systems. This review intends both to introduce the active field of current research, as well as to provide an accurate summary of the development of the field to date. A QPC consists essentially of a short, narrow constriction connecting two conducting reservoirs, and is illustrated in the micrograph. Silicon based QPC systems can be subdivided into essentially two categories: those defined in the two-dimensional electron gas (2DEG) formed in the inversion layer of a Si-MOSFET, and those systems based upon Si/SiGe heterostructures. The stacked-gate geometry employed in the realization of a Si-based QPC device is schematically illustrated. AlGaAs/GaAs heterostructures remain the system of choice for the majority of experiments on ballistic QPCs. The split-gate geometry extensively used for the fabrication of heterostructure based QPC devices is schematically illustrated. Other III-V heterostructure material systems have also been successfully employed in the fabrication of QPC devices. The definition of the active region of a QPC device necessarily requires some form of high-resolution lithography. Electron-beam lithography is certainly the most widely exploited technique which has been employed for this purpose. QPCs have also been fabricated using conventional optical contact lithography. More recently scanning probe microscopes have also been employed for QPC fabrication.

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2 Overview of systems
Book Title
Electronic Transport. Part 1: Quantum Point Contacts and Quantum Wires
II Quantum point contacts
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Landolt-Börnstein - Group III Condensed Matter
  • B. Kramer
  • Authors
  • D. Wharam
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