Related Experiment Video
Updated: Jul 24, 2026
06:43
Writing and Low-Temperature Characterization of Oxide Nanostructures
Published on: July 18, 2014
Weak localization, hole-hole interactions, and the "Metal"-insulator transition in two dimensions
1Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 OHE, United Kingdom and Semiconductor Nanofabrication Facility, University of New South Wales, Sydney 2052, Australia.
Physical Review Letters
|October 6, 2000
Summary
Quantum corrections affect metallic behavior in GaAs-AlGaAs 2D hole systems. Even at low densities, weak localization and interactions suggest no true metallic phase exists in two dimensions.
Area of Science:
- Condensed Matter Physics
- Semiconductor Heterostructures
- Quantum Phenomena
Background:
- Two-dimensional hole systems (2DHS) in GaAs-AlGaAs heterostructures are crucial for studying fundamental physics.
- Understanding metallic behavior in low-density, high-quality systems is challenging.
- Quantum effects are known to influence electronic properties at low temperatures.
Purpose of the Study:
- To investigate the metallic behavior in high-quality GaAs-AlGaAs two-dimensional hole systems.
- To identify and characterize quantum corrections to resistivity and Hall constant.
- To determine the existence of a true metallic phase in two dimensions at low densities.
Main Methods:
- Detailed investigation of resistivity and Hall effect measurements.
- Analysis of temperature-dependent resistivity to identify metallic behavior.
- Measurement of magnetoresistance to detect weak localization.
- Evaluation of Hall constant corrections due to interactions.
Main Results:
- Quantum corrections to resistivity were observed at low temperatures in the metallic phase.
- Weak localization, indicated by negative magnetoresistance, was present.
- Weak hole-hole interactions, affecting the Hall constant, were also detected.
- Resistivity decreased with decreasing temperature, characteristic of a metallic phase.
Conclusions:
- Quantum corrections, including weak localization and interactions, are present in the metallic phase of 2DHS.
- These corrections persist even at high electron densities (r(s) > 10).
- The findings suggest that a true metallic phase may not exist in two dimensions at these high r(s) values if quantum corrections persist to absolute zero.
More Related Videos
09:26In Situ Time-dependent Dielectric Breakdown in the Transmission Electron Microscope: A Possibility to Understand the Failure Mechanism in Microelectronic Devices
Published on: June 26, 2015
05:39Scalable Quantum Integrated Circuits on Superconducting Two-Dimensional Electron Gas Platform
Published on: August 2, 2019
Related Concept Videos
02:35Band Theory
When two or more atoms come together to form a molecule, their atomic orbitals combine and molecular orbitals of distinct energies result. In a solid, there are a large number of atoms, and therefore a large number of atomic orbitals that may be combined into molecular orbitals. These groups of molecular orbitals are so closely placed together to form continuous regions of energies, known as the bands.
The energy difference between these bands is known as the band gap.
Conductor, Semiconductor,...
The energy difference between these bands is known as the band gap.
Conductor, Semiconductor,...
01:12Fermi Level Dynamics
The vacuum level denotes the energy threshold required for an electron to escape from a material surface. It is usually positioned above the conduction band of a semiconductor and acts as a benchmark for comparing electron energies within various materials.
Electron affinity in semiconductors refers to the energy gap between the minimum of its conduction band and the vacuum level and it is a critical parameter in determining how easily a semiconductor can accept additional electrons.
The work...
Electron affinity in semiconductors refers to the energy gap between the minimum of its conduction band and the vacuum level and it is a critical parameter in determining how easily a semiconductor can accept additional electrons.
The work...
01:22Semiconductors
There is variation in the electrical conductivity of materials - metals, semiconductors, and insulators that are showcased with the help of the energy band diagrams.
Metals such as copper (Cu), zinc (Zn), or lead (Pb) have low resistivity and feature conduction bands that are either not fully occupied or overlap with the valence band, making a bandgap non-existent. This allows electrons in the highest energy levels of the valence band to easily transition to the conduction band upon gaining...
Metals such as copper (Cu), zinc (Zn), or lead (Pb) have low resistivity and feature conduction bands that are either not fully occupied or overlap with the valence band, making a bandgap non-existent. This allows electrons in the highest energy levels of the valence band to easily transition to the conduction band upon gaining...
01:24Metal-Semiconductor Junctions
The contact of metal and semiconductor can lead to the formation of a junction with either Schottky or Ohmic behavior.
Schottky Barriers
Schottky barriers arise when a metal with a work function (Φm) contacts a semiconductor with a different work function (Φs). Initially, electrons transfer until the Fermi levels of the metal and semiconductor align at equilibrium. For instance, if Φm > Φs, the semiconductor Fermi level is higher than the metal's before contact. The semiconductor's...
Schottky Barriers
Schottky barriers arise when a metal with a work function (Φm) contacts a semiconductor with a different work function (Φs). Initially, electrons transfer until the Fermi levels of the metal and semiconductor align at equilibrium. For instance, if Φm > Φs, the semiconductor Fermi level is higher than the metal's before contact. The semiconductor's...
01:27Biasing of Metal-Semiconductor Junctions
Biasing metal-semiconductor junctions involves applying a voltage across the junction. Specifically, the metal is connected to a voltage source, while the semiconductor is grounded. This technique is essential for controlling the direction and magnitude of current flow in electronic devices, including diodes, transistors, and photovoltaic cells.
In Schottky junctions, where the semiconductor is n-type, applying a positive voltage to the metal relative to the semiconductor reduces its Fermi...
In Schottky junctions, where the semiconductor is n-type, applying a positive voltage to the metal relative to the semiconductor reduces its Fermi...
01:26Imperfections in Crystal Structure: Stoichiometric Point Defects
Schottky defects arise when some lattice points in a crystal, such as those in NaCl, remain unoccupied, creating lattice vacancies without disturbing the overall electrical neutrality of the crystal. This defect is common in ionic crystals where the positive and negative ions are similar in size, as seen in sodium chloride and cesium chloride. The presence of Schottky defects enables the crystal to conduct electricity to a small extent through an ionic mechanism. Electric fields cause nearby...