Terahertz Ionization of Highly Charged Quantum Posts in a Perforated Electron Gas

Christopher M Morris; Dominik Stehr; Hyochul Kim; Tuan-Anh Truong; Craig Pryor; Pierre M Petroff; Mark S Sherwin

doi:10.1021/nl1044154

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Terahertz Ionization of Highly Charged Quantum Posts in a Perforated Electron Gas

Journal article

Peer reviewed

Terahertz Ionization of Highly Charged Quantum Posts in a Perforated Electron Gas

Christopher M Morris, Dominik Stehr, Hyochul Kim, Tuan-Anh Truong, Craig Pryor, Pierre M Petroff and Mark S Sherwin

Nano letters, Vol.12(3), pp.1115-1120

2012

DOI: 10.1021/nl1044154

PMID: 21517124

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Abstract

“Quantum posts” are roughly cylindrical semiconductor nanostructures that are embedded in an energetically shallower “matrix” quantum well of comparable thickness. We report measurements of voltage-controlled charging and terahertz absorption of 30 nm thick InGaAs quantum wells and posts. Under flat-band (zero-electric field) conditions, the quantum posts each contain approximately six electrons, and an additional ∼2.4 × 1011 cm−2 electrons populate the quantum well matrix. In this regime, absorption spectra show peaks at 3.5 and 4.8 THz (14 and 19 meV) whose relative amplitude depends strongly on temperature. These peaks are assigned to intersubband transitions of electrons in the quantum well matrix. A third, broader feature has a temperature-independent amplitude and is assigned to an absorption involving quantum posts. Eight-band k·p calculations incorporating the effects of strain and Coulomb repulsion predict that the electrons in the posts strongly repel the electrons in the quantum well matrix, “perforating” the electron gas. The strongest calculated transition, which has a frequency close to the center of the quantum post related absorption at 5 THz (20 meV), is an ionizing transition from a filled state to a quasi-bound state that can easily scatter to empty states in the quantum well matrix.

Materials Science

Physics

Condensed matter: electronic structure, electrical, magnetic, and optical properties

Condensed matter: structure, mechanical and thermal properties

Cross-disciplinary physics: materials science; rheology

Exact sciences and technology

Fullerenes and related materials

Low-dimensional structures (superlattices, quantum well structures, multilayers): structure, and nonelectronic properties

Nanocrystalline materials

Nanoscale materials and structures: fabrication and characterization

Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation

Quantum wells

Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties)

Visible and ultraviolet spectra

Details

Title: Subtitle: Terahertz Ionization of Highly Charged Quantum Posts in a Perforated Electron Gas
Creators: Christopher M Morris - University of California, Santa Barbara
Dominik Stehr - Helmholtz-Zentrum Dresden-Rossendorf
Hyochul Kim - University of Maryland, College Park
Tuan-Anh Truong - University of California, Santa Barbara
Craig Pryor - University of Iowa
Pierre M Petroff - University of California, Santa Barbara
Mark S Sherwin - University of California, Santa Barbara
Resource Type: Journal article
Publication Details: Nano letters, Vol.12(3), pp.1115-1120
Publisher: American Chemical Society
DOI: 10.1021/nl1044154
PMID: 21517124
ISSN: 1530-6984
eISSN: 1530-6992
Language: English
Date published: 2012
Academic Unit: Physics and Astronomy
Record Identifier: 9984199694802771

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