Structural and optical properties of MBE‐grown asymmetric cubic GaN/AlxGa1–xN double quantum wells

Wecker, T.; Hörich, Florian; Feneberg, Martin; Goldhahn, R.; Reuter, D.; As, D. J.

doi:10.1002/pssb.201451531

Cited by 15 publications

(14 citation statements)

References 25 publications

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“…Previous investigation on a similar ADQW structure with an Al content of 0.26 revealed coupling to start at 5 nm thick barriers. [24] For our samples the Al content is with 0.64 much higher, leading to a greater potential offset at the GaN/AlGaN interface. Thus the coupling starts for thinner barriers (below 3 nm).…”

Section: Discussionmentioning

confidence: 83%

Correlation of the Carrier Decay Time and Barrier Thickness for Asymmetric Cubic GaN/Al_0.64Ga_0.36N Double Quantum Wells

Wecker

Callsen

Hoffmann

et al. 2017

Physica Status Solidi (b)

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The carrier transfer via non‐resonant tunneling is of great significance for many devices like the quantum cascade laser. In this study time‐resolved photoluminescence is used for an investigation of this effect in asymmetric double quantum wells for low temperatures. The Al content in these asymmetric double quantum wells was determined by HRXRD to x = 0.64 ± 0.03. The growth of the asymmetric cubic GaN/AlxGa1−xN double quantum wells was performed by a radio‐frequency plasma‐assisted molecular beam epitaxy. As a substrate, 3C‐SiC (001) on top of Si (001) was used. Three samples with different barrier thickness d were analysed (1 nm, 3 nm, 15 nm). The two quantum wells are designed with the thicknesses 2.5 nm and 1.35 nm. Thus, three expected emission bands measured in luminescence can be resolved. The maximum intensities are 3.49 eV (wide well), 3.73 eV (narrow well) and 4.12 eV (AlGaN). A correlation between the carrier lifetimes of the quantum wells (QWs) and the barrier width is found. Exploiting rate equations, the intensity ratio of both QW emissions is calculated. The coupling of the two QWs starts below 3 nm barrier thickness, above this value there is no coupling.

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Section: Discussionmentioning

confidence: 83%

Correlation of the Carrier Decay Time and Barrier Thickness for Asymmetric Cubic GaN/Al_0.64Ga_0.36N Double Quantum Wells

Wecker

Callsen

Hoffmann

et al. 2017

Physica Status Solidi (b)

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“…The Burgers vector for a dislocation in a cubic zinc‐blende crystal, such as c‐GaN, is given by

b = a / \sqrt{2}

, where a is the lattice parameter (). The lattice constant for c‐GaN is taken to be

a = 4.503 Å

. The calculated values for the dislocation densities are summarized in Table .…”

Section: Resultsmentioning

confidence: 99%

Joint Raman spectroscopy and HRXRD investigation of cubic gallium nitride layers grown on 3C-SiC

Rüsing

Wecker

Berth

et al. 2016

Phys. Status Solidi B

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Abstractauthoren Cubic gallium nitride (GaN) films are analyzed with high‐resolution X‐ray diffraction (HRXRD) and Raman spectroscopy. Several cubic GaN layers were grown on 3C‐SiC (001) substrate by radio‐frequency plasma‐assisted molecular beam epitaxy. The layer thickness of the cubic GaN was varied between 75 and 505 nm. The HRXRD analysis reveals a reduction of the full‐width at half‐maximum (FWHM) of omega scans for growing layer thicknesses, which is caused by a partial compensation of defects. The Raman characterization confirms well‐formed c‐GaN layers. A more detailed examination of the longitudinal optical mode hints at a correlation of the FWHM of the Raman mode with the dislocation density, which shows the possibility to determine dislocation densities by Raman spectroscopy on a micrometer scale, which is not possible by HRXRD. Furthermore, this Raman analysis shows that normalized Raman spectra present an alternative way to determine layer thicknesses of thin GaN films.

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“…The parameters used for nextnanoþþ can be looked up in Ref. [20] . Wecker et al have shown that the parameters they used fit very well for the calculation of the interband and intraband transitions of c-GaN quantum wells with nextnano3, so we expect comparably good results.…”

Section: Nextnanoþþ Simulationsmentioning

confidence: 99%

Optical Properties of Cubic GaN Quantum Dots Grown by Molecular Beam Epitaxy

Blumenthal

Reuter

2018

Physica Status Solidi (b)

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We have investigated the optical properties of self‐assembled cubic GaN quantum dots (QDs) in a cubic AlN matrix grown in Stranski–Krastanov growth mode. Two different sample series are fabricated and optically characterized by photoluminescence measurements. Additionally, the experimental results are compared to theoretical calculations. Sample series A consists of one single QD layer with varying GaN amount. A red shift of emission energy of 140 meV is observed with increasing GaN deposition time. Simulations verify this behavior and can be explained by a decrease of the QD height. Sample series B has two layers of QDs on top of each other with different QD deposition amounts of three and six monolayers, respectively. The spacer layer thickness between the QD layers is 2 and 20 nm. A decreased emission intensity of the smaller QDs is measured for QD layers with smaller spacer layer thickness. This observation is a first hint of an electronic coupling between the two QD layers with thin spacer layer thickness resulting in tunneling of carriers from the smaller QDs to the larger QDs. Theoretical calculations further show that a strain induced structural coupling induces a vertical alignment of the QDs.

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Structural and optical properties of MBE‐grown asymmetric cubic GaN/Al_xGa_1–xN double quantum wells

Cited by 15 publications

References 25 publications

Correlation of the Carrier Decay Time and Barrier Thickness for Asymmetric Cubic GaN/Al_0.64Ga_0.36N Double Quantum Wells

Correlation of the Carrier Decay Time and Barrier Thickness for Asymmetric Cubic GaN/Al_0.64Ga_0.36N Double Quantum Wells

Joint Raman spectroscopy and HRXRD investigation of cubic gallium nitride layers grown on 3C-SiC

Optical Properties of Cubic GaN Quantum Dots Grown by Molecular Beam Epitaxy

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Structural and optical properties of MBE‐grown asymmetric cubic GaN/AlxGa1–xN double quantum wells

Cited by 15 publications

References 25 publications

Correlation of the Carrier Decay Time and Barrier Thickness for Asymmetric Cubic GaN/Al0.64Ga0.36N Double Quantum Wells

Correlation of the Carrier Decay Time and Barrier Thickness for Asymmetric Cubic GaN/Al0.64Ga0.36N Double Quantum Wells

Joint Raman spectroscopy and HRXRD investigation of cubic gallium nitride layers grown on 3C-SiC

Optical Properties of Cubic GaN Quantum Dots Grown by Molecular Beam Epitaxy

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Structural and optical properties of MBE‐grown asymmetric cubic GaN/Al_xGa_1–xN double quantum wells

Correlation of the Carrier Decay Time and Barrier Thickness for Asymmetric Cubic GaN/Al_0.64Ga_0.36N Double Quantum Wells

Correlation of the Carrier Decay Time and Barrier Thickness for Asymmetric Cubic GaN/Al_0.64Ga_0.36N Double Quantum Wells