Light emission ranging from blue to red from a series of InGaN/GaN single quantum wells

Martin, Robert; Edwards, P. R.; Pecharromán-Gallego, R; Liu, C; Deatcher, C. J.; Watson, I. M.; O'Donnell, K.P.

doi:10.1088/0022-3727/35/7/306

Cited by 39 publications

(38 citation statements)

References 21 publications

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“…For a variation of the InGaN growth temperature or In/Ga ratio high intensities in the longer wavelength region are achieved. We observe an exponentially decreasing PL intensity for longer wavelengths and an intensity ratio for the blue to red-orange emission around 12:1, similar to samples grown on sapphire [7].…”

Section: Movpe Growth Of Ingansupporting

confidence: 74%

Gallium‐nitride‐based devices on silicon

Dadgar

Poschenrieder

Daumiller

et al. 2003

phys. stat. sol. (c)

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GaN devices on Si are interesting for low-cost, high-power devices as LEDs and FETs. Until recently, most LED and FET devices suffered from cracking and low output power and additionally, from high series resistances for vertically contacted LEDs. Here, we give a brief overview on state of the art crackfree, bright LEDs with an output power up to 0.42 mW and AlGaN/GaN FETs with an output power of 2.5 W/mm at 2 GHz.

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Section: Movpe Growth Of Ingansupporting

confidence: 74%

Gallium‐nitride‐based devices on silicon

Dadgar

Poschenrieder

Daumiller

et al. 2003

phys. stat. sol. (c)

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“…There is also an increase in the strength of the phonon replicas relative to the zero-phonon recombination with increasing indium fraction. The trend of an increasing strength of the phonon replicas relative to the zero-phonon recombination with decreasing zero-phonon peak energy has also been observed in In 0.17 Ga 0.83 N/GaN quantum wells and quantum boxes of different dimensions [5,6] and in InGaN/GaN quantum wells with different indium contents [7].…”

Section: Methodsmentioning

confidence: 54%

“…Using this procedure, we found that all the spectra had phonon replicas separated by 91 meV, with no dependence on composition. Martin et al [7] have also reported LO phonon energies close to 90 meV independent of indium content in the quantum well.…”

Section: Methodsmentioning

confidence: 87%

Exciton localization in InGaN/GaN single quantum well structures

Graham

Vala

Dawson

et al. 2003

Physica Status Solidi (b)

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We have performed a detailed investigation of the low temperature (T = 6 K) photoluminescence spectra and recombination lifetimes of localized excitons in a set of InGaN/GaN single quantum wells in which the indium fraction in the quantum well was varied. We found that with increasing indium fraction the photoluminescence peak emission moved to lower energy and the intensities of the phonon replicas relative to the zero-phonon line increased. From a multi-Gaussian fit of the experimental data, we extracted the Huang-Rhys factor (S), a measure of the strength of the exciton coupling with LO-phonons. By comparing experimental S factors with the results of a theoretical model, we found that the excitons localize on a length scale of ~2 nm in our samples.1 Introduction In InGaN/GaN quantum well structures, it is widely believed that injected carriers are localized in space. The principal effects of localization are the suppression of non-radiative recombination mechanisms and a red shift in the peak energy of the inhomogeneously broadened spontaneous emission spectrum. If improvements are to be made in the performance of InGaN/GaN LEDs and lasers, the precise nature of the carrier localization has to be understood in detail.One consequence of carrier localization in InGaN/GaN quantum wells is the appearance of strong LO phonon accompanied recombination [1] that results from the lattice distortion caused by the electric field of the exciton. In this work, we have used the theory first developed by Huang and Rhys describing the intensity distribution of the zero-phonon (E 0 ) and phonon replica (E 0 − nħω LO ) recombination [2] to extract the so called Huang-Rhys factor S, a measure of the strength of the exciton LO-phonon coupling, for a set of InGaN/GaN single quantum wells with different indium fractions. By comparing experimental and calculated S values, we have determined the localization length scale for the excitons, a scale comparable to the contrast variations observed in our high-resolution transmission electron microscopy images of the quantum wells.

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“…6 These materials can emit light from the ultra-violet (UV) region through the visible and to the infra-red. 7 To produce highly efficient blue-emitting LEDs a series of thin InGaN layers are grown between several GaN layers creating a multi-quantum well structure, aiding carrier confinement and increased radiative recombination. Utilising hybrid inorganic/organic LED architectures offers the opportunity to combine the advantages of both technologies; the well-understood and high-performing electronic properties of inorganic LEDs with the broad, tunable emission of organic semiconducting materials.…”

Section: Introductionmentioning

confidence: 99%

Cool to warm white light emission from hybrid inorganic/organic light-emitting diodes

et al. 2016

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The synthesis and characterisation of two novel organic down-converting molecules is disclosed, together with their performance as functional colour-converters in combination with inorganic blue light-emitting diodes (LEDs). Each molecule contains two fluorene-triphenylamine arms, connected to either a benzothiadiazole or bisbenzothiadiazole core. These molecules have been selected on the basis that they are free from absorption bands in the green region of the visible spectrum to maximise their performance and offer improvements compared with previous BODIPY-containing analogues. The inorganic InGaN/GaN LED emits at 444 nm, overlying the absorption of each of the organic molecules.The combination of the blue (inorganic) and yellow (organic) emission is shown to produce reasonable quality, white light-emitting hybrid devices for both down-converter molecules. Cool to warm white light is achieved for both molecules by increasing the concentration. An optimum colour rendering index (CRI) value of 66 is obtained for the mono-benzothiadiazole molecule. Also a high blue-to-white efficacy (defined as white luminous flux (lm)/blue radiant flux (W)) of 368 lm W À1 is achieved, superseding the current phosphor converters of 200-300 lm W À1. A comparison of these down-converting molecules to the older generation BODIPY-containing molecules is also provided.

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Light emission ranging from blue to red from a series of InGaN/GaN single quantum wells

Cited by 39 publications

References 21 publications

Gallium‐nitride‐based devices on silicon

Gallium‐nitride‐based devices on silicon

Exciton localization in InGaN/GaN single quantum well structures

Cool to warm white light emission from hybrid inorganic/organic light-emitting diodes

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