Landolt-Börnstein - Group III Condensed Matter

7.1 Geometrical quantization

Abstract

This chapter discusses geometrical quantization of quantum wires. In a quantum wire, the carriers are confined along two directions. The energy bands of such a system can be calculated by solving a Schrodinger equation. The quantized energy spectrum is directly observable experimentally via magnetic depopulation or quantized conductance. This chapter includes literature on magnetic depopulation of 1D subbands and quantized conductance. Magnetoresistance (MR) curves at 40mK for an 80 nm and a 310 nm wide InGaAs wire are illustrated. SdH oscillations were periodic in a 310nm wide wire and non-periodic in a 80 nm wide wire, indicating a 1D energy spectrum. A MR peak due to boundary scattering was found around ≈0.75 T, peak resistance and corresponding magnetic field increased as the wire width decreased. Conductance is plotted as a function of time after switching off an LED. With an increasing magnetic field the number of visible steps was reduced and step height increased. The dependence of conductance on a gate voltage (at T = 105 K) and on the wire length was studied. Differential conductance of a 2 μm long GaAs wire in a 25nm thick quantum well is illustrated. The temperature dependence of the conductance was stronger in the longer wires.

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Title
7.1 Geometrical quantization
Book Title
Electronic Transport. Part 1: Quantum Point Contacts and Quantum Wires
In
7 Single wires
Book DOI
10.1007/b55682
Chapter DOI
10.1007/10479560_38
Part of
Landolt-Börnstein - Group III Condensed Matter
Volume
34B1
Editors
  • B. Kramer
  • Authors
  • A. Fechner
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