Analysis of statistical compositional alloy fluctuations in InGaN from aberration corrected transmission electron microscopy image series

Schulz, Tobias; Remmele, T.; Markurt, Toni; Korytov, Maxim; Albrecht, M.

doi:10.1063/1.4742015

Cited by 31 publications

(21 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…There is no evidence of phase separation in the InGaN quantum wells nor any composition fluctuations beyond the random distribution of In atoms. 25 Therefore, the optical properties of such a QW sample will not be dominated by any Ininduced potential fluctuations.…”

Section: Discussionmentioning

confidence: 99%

“…6 for an example) preclude In-clusters and yield an In content of 19% with a completely random distribution of the In atoms. 25 Please note that a pronounced In-clustering would be required in order to explain localization over the entire spectral range of the CHC luminescence reaching up to 0.4 eV above the QW ground-state transition. In addition, such In-clustering would result in strong non-monotonicity FIG.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Polarization-induced confinement of continuous hole-states in highly pumped, industrial-grade, green InGaN quantum wells

Nippert

Nirschl

Schulz

et al. 2016

Journal of Applied Physics

View full text Add to dashboard Cite

We investigate industrial-grade InGaN/GaN quantum wells (QWs) emitting in the green spectral region under high, resonant pumping conditions. Consequently, an ubiquitous high energy luminescence is observed that we assign to a polarization field Confined Hole Continuum (CHC). Our finding is supported by a unique combination of experimental techniques, including transmission electron microscopy, (time-resolved) photoluminescence under various excitation conditions, and electroluminescence, which confirm an extended out-of-plane localization of the CHC-states. The larger width of this localization volume surpasses the QW thickness, yielding enhanced nonradiative losses due to point defects and interfaces, whereas the energetic proximity to the bulk valence band states promotes carrier leakage. Published by AIP Publishing.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Polarization-induced confinement of continuous hole-states in highly pumped, industrial-grade, green InGaN quantum wells

Nippert

Nirschl

Schulz

et al. 2016

Journal of Applied Physics

View full text Add to dashboard Cite

show abstract

“…For both QWs and the QB, the histograms are well described by Gaussian distributions indicating that the In distribution in our N-polar In x Ga 1−x N/In y Ga 1−y N QWs is essentially random. 42 Hence, the anomalous dependence of emission energy and intensity cannot be ascribed to carrier localization by strong, non-random alloy fluctuations. …”

Section: Transmission Electron Microscopymentioning

confidence: 99%

“…The local lattice parameter was obtained using the algorithm developed in Ref. 42. Since the QWs are coherently strained, the local lattice parameter c reflects the distribution of the In content inside the QWs.…”

Section: Transmission Electron Microscopymentioning

confidence: 99%

Comparison of the Luminous Efficiencies of Ga- and N-PolarInxGa1−xN/In
Fernández-Garrido
¹
,
Lähnemann
²
,
Hauswald
³

et al. 2016
Phys. Rev. Applied
17
1
14
0
View full text Add to dashboard Cite

We investigate the luminescence of Ga-and N-polar In x Ga 1−x N/In y Ga 1−y N quantum wells grown by plasma-assisted molecular beam epitaxy on freestanding GaN as well as 6H-SiC substrates. In striking contrast to their Ga-polar counterparts, the N-polar quantum wells prepared on freestanding GaN do not exhibit any detectable photoluminescence even at 10 K. Theoretical simulations of the band profiles combined with resonant excitation of the quantum wells allow us to rule out carrier escape and subsequent surface recombination as the reason for this absence of luminescence. To explore the hypothesis of a high concentration of nonradiative defects at the interfaces between wells and barriers, we analyze the photoluminescence of Ga-and N-polar quantum wells prepared on 6H-SiC as a function of the well width. Intense luminescence is observed for both Ga-and N polar samples. As expected, the luminescence of the Ga-polar quantum wells quenches and red-shifts with increasing well width due to the quantum confined Stark effect. In contrast, both the intensity and the energy of the luminescence from the N-polar samples are essentially independent of well width. Transmission electron microscopy reveals that the N-polar quantum wells exhibit abrupt interfaces and homogeneous composition, excluding emission from In-rich clusters as the reason for this anomalous behavior. The microscopic origin of the luminescence in the N-polar samples is elucidated using spatially resolved cathodoluminescence spectroscopy. Regardless of well width, the luminescence is found to not originate from the N-polar quantum wells, but from the semipolar facets of ∨-pit defects. These results cast serious doubts on the potential of N-polar In x Ga 1−x N/In y Ga 1−y N quantum wells grown by plasma-assisted molecular beam epitaxy for the development of long-wavelength light emitting diodes. What remains to be seen is whether unconventional growth conditions may enable a significant reduction in the concentration of nonradiative defects.

show abstract

“…In this respect, investigating the optical properties of high-quality InGaN epilayers grown on c-plane free-standing (FS) GaN substrates should prove complementary to recent structural information, namely, compositional mapping, obtained on InGaN QWs using TEM. 25,26 One important aspect deals with the further elucidation of the driving mechanisms behind alloy disorder, whose weight as a function of indium content can be probed via the combination of optical absorption (OA) and near-field (2018) optical measurements. In particular, one interesting outcome would consist in establishing a more comprehensive connection between the optical properties of those layers and the surface morphology induced by InGaN growth conditions, namely, step-meandering.…”

Section: à2mentioning

confidence: 99%

Optical absorption edge broadening in thick InGaN layers: Random alloy atomic disorder and growth mode induced fluctuations

Butté

Lahourcade

Uždavinys

et al. 2018

Applied Physics Letters

View full text Add to dashboard Cite

To assess the impact of random alloying on the optical properties of the InGaN alloy, high-quality InxGa1−xN (0 < x < 0.18) epilayers grown on c-plane free-standing GaN substrates are characterized both structurally and optically. The thickness (25–100 nm) was adjusted to keep these layers pseudomorphically strained over the whole range of explored indium content as checked by x-ray diffraction measurements. The evolution of the low temperature optical absorption (OA) edge linewidth as a function of absorption energy, and hence the indium content, is analyzed in the framework of the random alloy model. The latter shows that the OA edge linewidth should not markedly increase above an indium content of 4%, varying from 17 meV to 30 meV for 20% indium. The experimental data initially follow the same trend with, however, a deviation from this model for indium contents exceeding only ∼2%. Complementary room temperature near-field photoluminescence measurements carried out using a scanning near-field optical microscope combined with simultaneous surface morphology mappings reveal spatial disorder due to growth meandering. We conclude that for thick high-quality pseudomorphic InGaN layers, a deviation from pure random alloying occurs due to the interplay between indium incorporation and longer range fluctuations induced by the InGaN step-meandering growth mode.

show abstract

Analysis of statistical compositional alloy fluctuations in InGaN from aberration corrected transmission electron microscopy image series

Cited by 31 publications

References 27 publications

Polarization-induced confinement of continuous hole-states in highly pumped, industrial-grade, green InGaN quantum wells

Polarization-induced confinement of continuous hole-states in highly pumped, industrial-grade, green InGaN quantum wells

Comparison of the Luminous Efficiencies of Ga- and N-PolarInxGa1−xN/In
Fernández-Garrido
¹
,
Lähnemann
²
,
Hauswald
³

et al. 2016
Phys. Rev. Applied
17
1
14
0
View full text Add to dashboard Cite

Optical absorption edge broadening in thick InGaN layers: Random alloy atomic disorder and growth mode induced fluctuations

Contact Info

Product

Resources

About

Analysis of statistical compositional alloy fluctuations in InGaN from aberration corrected transmission electron microscopy image series

Cited by 31 publications

References 27 publications

Polarization-induced confinement of continuous hole-states in highly pumped, industrial-grade, green InGaN quantum wells

Polarization-induced confinement of continuous hole-states in highly pumped, industrial-grade, green InGaN quantum wells

Comparison of the Luminous Efficiencies of Ga- and N-PolarInxGa1−xN/InFernández-Garrido1, Lähnemann2, Hauswald3 et al. 2016Phys. Rev. Applied171140View full textAdd to dashboardCite

Optical absorption edge broadening in thick InGaN layers: Random alloy atomic disorder and growth mode induced fluctuations

Contact Info

Product

Resources

About

Comparison of the Luminous Efficiencies of Ga- and N-PolarInxGa1−xN/In
Fernández-Garrido
¹
,
Lähnemann
²
,
Hauswald
³

et al. 2016
Phys. Rev. Applied
17
1
14
0
View full text Add to dashboard Cite