Cathodoluminescence in semiconductor structures under local tunneling electron injection

Abstract : The thesis objective is to study transport and recombination phenomena at the nanoscale in semiconductor structures incorporating quantum wells. The experimental approach consists in injecting electrons locally by the tip of a scanning tunneling microscope and detecting the luminescence due to the recombination of electrons transmitted through the structure and captured by the quantum wells inserted at a distance from the surface. This all-optical measurement overcomes some of the limitations associated with usual techniques based on the electrical measurement of very small transmitted currents. In particular, it should allow addressing hot-electron transport through isolated nanostructures or through non-rectifying heterostructures, mapping electronic transport down to ultimate scales eventually in contacted devices under operation, exploiting spin filtering effects in ferromagnetic metal/semiconductor junctions. The main results obtained in the present work concerns the study GaN / InGaN / GaN structures that form the basis of wide-bandgap light-emitting devices for lighting. Excitation spectroscopy of the cathodoluminescence, obtained by measuring the light emitted from the InGaN quantum wells as a function of the electron injection energy, shows two regimes which may be related to the condumicroscopie à l'effet tunnelction band structure. Imaging of the cathodoluminescence evidences localization effects on the transport and radiative recombination process. These localization effects can be due to the disorder in the InGaN ternary alloy composition. Moreover, the severe tunneling injection conditions required to investigate minority carrier transport in large bandgap p-type semiconductor structures produce significant changes in the surface composition and morphology. The exploitation of these phenomena allowed us to control the formation of tip-induced patterns of nanometric dimensions on the GaN surface.
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Contributor : Petr Polovodov <>
Submitted on : Tuesday, July 19, 2016 - 4:23:50 PM
Last modification on : Thursday, January 11, 2018 - 6:25:43 AM

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  • HAL Id : tel-01346834, version 1

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Petr Polovodov. Cathodoluminescence in semiconductor structures under local tunneling electron injection. Physics [physics]. Ecole Doctorale de l'Ecole Polytechnique, 2015. English. ⟨tel-01346834v1⟩

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