Publication

Imaging Nonradiative Point Defects Buried in Quantum Wells Using Cathodoluminescence

Nicolas Grandjean, Jean-François Carlin, Raphaël Butté, Duncan Thomas Lindsay Alexander, Wei Liu, Wei Liu, Thomas Fjord Kjaersgaard Weatherley
2021
Journal Articles

Abstract

Crystallographic point defects (PDs) can dramatically decrease the efficiency of optoelectronic semiconductor devices, many of which are based on quantum well (QW) heterostructures. However, spatially resolving individual nonradiative PDs buried in such QWs has so far not been demonstrated. Here, using high-resolution cathodoluminescence (CL) and a specific sample design, we spatially resolve, image, and analyze nonradiative PDs in InGaN/GaN QWs at the nanoscale. We identify two different types of PDs by their contrastin behavior with temperature and measure their densities from 10(14) cm(-3) to as high as 10(16) cm(-3). Our CL images clearly illustrate the interplay between PDs and carrier dynamics in the well: increasing PD concentration severely limits carrier diffusion lengths, while a higher carrier density suppresses the nonradiative behavior of PDs. The results in this study are readily interpreted directly from CL images and represent a significant advancement in nanoscale PD analysis.

Official source

https://infoscience.epfl.ch/entities/publication/231c7525-71ff-4fb5-a7a1-4bcf3b4492e9

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Nicolas Grandjean, Jean-François Carlin, Raphaël Butté, Duncan Thomas Lindsay Alexander, Wei Liu, Wei Liu, Thomas Fjord Kjaersgaard Weatherley
2021
Journal Articles

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/231c7525-71ff-4fb5-a7a1-4bcf3b4492e9

About this result

Related concepts (26)

Doping (semiconductor)

In semiconductor production, doping is the intentional introduction of impurities into an intrinsic semiconductor for the purpose of modulating its electrical, optical and structural properties. The doped material is referred to as an extrinsic semiconductor. Small numbers of dopant atoms can change the ability of a semiconductor to conduct electricity. When on the order of one dopant atom is added per 100 million atoms, the doping is said to be low or light.

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.

Crystallographic defect

A crystallographic defect is an interruption of the regular patterns of arrangement of atoms or molecules in crystalline solids. The positions and orientations of particles, which are repeating at fixed distances determined by the unit cell parameters in crystals, exhibit a periodic crystal structure, but this is usually imperfect. Several types of defects are often characterized: point defects, line defects, planar defects, bulk defects. Topological homotopy establishes a mathematical method of characterization.

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