Publication

Intersubband scattering rates in GaAs quantum wells under selective and resonant excitation, measured by femtosecond luminescence

Benoît Marie Joseph Deveaud, Stefan Haacke
1997
Journal Articles

Abstract

Using luminescence upconversion with 100 fs resolution, we have investigated the intersubband scattering of electrons in GaAs quantum wells (QWs). The energy separations between the first and second confined electron subband (E(12)) were more or less than the LO phonon energy (E(LO)) In narrow QWs (E(12) > E(LO)) the intrinsic LO phonon scattering rate is found to be 1.6 x 10(12) s(-1). A Monte Carlo simulation allows us to reproduce the experimental data with high accuracy. In wide QWs (E(12) < E(LO)) We find a very fast thermalization of the carrier population in the QW within times shorter than 300 fs. The intersubband relaxation rate for electrons in the n = 2 subband can be estimated to be shorter than 1.5 ps. (C) 1997 Academic Press Limited

Official source

https://infoscience.epfl.ch/entities/publication/7ec2e10f-a091-4b11-81e9-eb41037ce1ca

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Benoît Marie Joseph Deveaud, Stefan Haacke
1997
Journal Articles

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/7ec2e10f-a091-4b11-81e9-eb41037ce1ca

About this result

Related concepts (22)

Quantum well

A quantum well is a potential well with only discrete energy values. The classic model used to demonstrate a quantum well is to confine particles, which were initially free to move in three dimensions, to two dimensions, by forcing them to occupy a planar region. The effects of quantum confinement take place when the quantum well thickness becomes comparable to the de Broglie wavelength of the carriers (generally electrons and holes), leading to energy levels called "energy subbands", i.e.

Photoluminescence

Photoluminescence (abbreviated as PL) is light emission from any form of matter after the absorption of photons (electromagnetic radiation). It is one of many forms of luminescence (light emission) and is initiated by photoexcitation (i.e. photons that excite electrons to a higher energy level in an atom), hence the prefix photo-. Following excitation, various relaxation processes typically occur in which other photons are re-radiated.

Quantum dot

Quantum dots (QDs) – also called semiconductor nanocrystals, are semiconductor particles a few nanometres in size, having optical and electronic properties that differ from those of larger particles as a result of quantum mechanics. They are a central topic in nanotechnology and materials science. When the quantum dots are illuminated by UV light, an electron in the quantum dot can be excited to a state of higher energy. In the case of a semiconducting quantum dot, this process corresponds to the transition of an electron from the valence band to the conductance band.

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Intersubband scattering rates in GaAs quantum wells under selective and resonant excitation, measured by femtosecond luminescence

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