Publication

Lateral Transport in Gaas/Algaas Quantum-Wells

Jean-Daniel Ganière
1993
Journal Articles

Abstract

The lateral transport of excess carriers in metal organic chemical vapor deposition grown GaAs/AlxGa1-xAs(x=0.5) 20 angstrom thick single quantum well structures is studied by cathodoluminescence (CL) between 5 K less-than-or-equal-to T less-than-or-equal-to 170 K. Impurity and native defect related transitions are found to take place around grown-in dislocations where well thickness variations are also found. The CL intensity of free excitons and/or transitions involving impurities and native defects is measured as a function of distance from the dislocation to the point of excitation. Using a simple diffusion model, we are able to determine the hole diffusion length, L=1.5 mum, in slightly n-doped SQW. This represents a novel method for the direct determination of the diffusion length ih sufficiently defect-free material.

Official source

https://infoscience.epfl.ch/entities/publication/520d0af5-b442-4b3d-be94-56e6611b43f7

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Jean-Daniel Ganière
1993
Journal Articles

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/520d0af5-b442-4b3d-be94-56e6611b43f7

About this result

Related concepts (14)

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.

Diffusion

Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in Gibbs free energy or chemical potential. It is possible to diffuse "uphill" from a region of lower concentration to a region of higher concentration, like in spinodal decomposition. Diffusion is a stochastic process due to the inherent randomness of the diffusing entity and can be used to model many real-life stochastic scenarios.

Exciton

An exciton is a bound state of an electron and an electron hole which are attracted to each other by the electrostatic Coulomb force. It is an electrically neutral quasiparticle that exists in insulators, semiconductors and some liquids. The exciton is regarded as an elementary excitation of condensed matter that can transport energy without transporting net electric charge. An exciton can form when a material absorbs a photon of higher energy than its bandgap. This excites an electron from the valence band into the conduction band.

Related publications (5)

Lateral Transport in Gaas/Algaas Quantum-Wells

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Use of quantitative EELS and cathodoluminescence for study of carrier confinement and diffusion in self organized vertical quantum wells

Near-field autocorrelation spectroscopy of disordered semiconductor quantum wells

Interferometric analysis of resonant Rayleigh scattering from two-dimensional excitons