Visualizing highly localized luminescence in GaN/AlN heterostructures in nanowires

Zagonel, Luiz Fernando; Rigutti, Lorenzo; Tchernycheva, Maria; Jacopin, Gwenolé; Songmuang, R.; Kociak, Mathieu

doi:10.1088/0957-4484/23/45/455205

Cited by 31 publications

(32 citation statements)

References 51 publications

(73 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The dimensions of these insertions are at the limit of the spatial resolution and thus individual insertions are not clearly resolved in SEM-based CL. Nevertheless, diffusing carriers should be trapped in the closest insertion [43], and therefore, the resolution is limited by the scattering volume of the electron beam with a diameter of about 30 nm at V acc = 5 kV. Hence, the signal at a given point should include contributions from two to three insertions.…”

Section: (Inga)n Luminescence Bandmentioning

confidence: 99%

Localization and defects in axial (In,Ga)N/GaN nanowire heterostructures investigated by spatially resolved luminescence spectroscopy

Lähnemann¹,

Hauswald²,

Wölz³

et al. 2014

J. Phys. D: Appl. Phys.

View full text Add to dashboard Cite

Abstract. (In,Ga)N insertions embedded in self-assembled GaN nanowires are of current interest for applications in solid-state light emitters. Such structures exhibit a notoriously broad emission band. We use cathodoluminescence spectral imaging in a scanning electron microscope and micro-photoluminescence spectroscopy on single nanowires to learn more about the mechanisms underlying this emission. We observe a shift of the emission energy along the stack of six insertions within single nanowires that may be explained by compositional pulling. Our results also corroborate reports that the localization of carriers at potential fluctuations within the insertions plays a crucial role for the luminescence of these nanowire based emitters. Furthermore, we resolve contributions from both structural and point defects in our measurements.

show abstract

Section: (Inga)n Luminescence Bandmentioning

confidence: 99%

Localization and defects in axial (In,Ga)N/GaN nanowire heterostructures investigated by spatially resolved luminescence spectroscopy

Lähnemann¹,

Hauswald²,

Wölz³

et al. 2014

J. Phys. D: Appl. Phys.

View full text Add to dashboard Cite

show abstract

“…Such requirements are better met by Transmission Electron Microscope operated in scanning mode (STEM) associated with high performance cathodoluminescence detectors (CL). [40,41] For a review, see ref. [42].…”

Section: Introductionmentioning

confidence: 99%

Nanometer-scale monitoring of quantum-confined Stark effect and emission efficiency droop in multiple GaN/AlN quantum disks in nanowires

et al. 2016

View full text Add to dashboard Cite

We report on a detailed study of the intensity dependent optical properties of individual GaN/AlN Quantum Disks (QDisks) embedded into GaN nanowires (NW). The structural and optical properties of the QDisks were probed by high spatial resolution cathodoluminescence (CL) in a scanning transmission electron microscope (STEM). By exciting the QDisks with a nanometric electron beam at currents spanning over 3 orders of magnitude, strong non-linearities (energy shifts) in the light emission are observed. In particular, we find that the amount of energy shift depends on the emission rate and on the QDisk morphology (size, position along the NW and shell thickness). For thick QDisks (>4nm), the QDisk emission energy is observed to blue-shift with the increase of the emission intensity. This is interpreted as a consequence of the increase of carriers density excited by the incident electron beam inside the QDisks, which screens the internal electric field and thus reduces the quantum confined Stark effect (QCSE) present in these QDisks. For thinner QDisks (<3 nm), the blue-shift is almost absent in agreement with the negligible QCSE at such sizes. For QDisks of intermediate sizes there exists a current threshold above which the energy shifts, marking the transition from unscreened to partially screened QCSE. From the threshold value we estimate the lifetime in the unscreened regime. These observations suggest that, counterintuitively, electrons of high energy can behave ultimately as single electron-hole pair generators. In addition, when we increase the current from 1 pA to 10 pA the light emission efficiency drops by more than one order of magnitude. This reduction of the emission efficiency is a manifestation of the 'efficiency droop' as observed in nitride-based 2D light emitting diodes, a phenomenon tentatively attributed to the Auger effect. *

show abstract

“…6e. In this case, the presence of a multi-QW system is meant to both limit the carrier diffusion [29] and to increase their recombination probability once the carriers are captured by the quantum wells. Another possibility, not shown here, is the so-called resonant excitation, consisting in creating carriers directly within quantum confining subsystems (quantum wells or dots), from which they could not freely diffuse.…”

Section: The Fib Bottleneckmentioning

confidence: 99%

Correlative Optical Spectroscopy and Atom Probe Tomography

Rigutti

2016

Acta Phys. Pol. A

View full text Add to dashboard Cite

This lecture will introduce and revise recent experimental developments on correlative laser-assisted atom probe tomography and optical spectroscopy, with a particular attention to the domain of semiconductor nanostructures. The main goal of correlative microscopy is to gain a deeper insight in materials science studies. For the materials scientist, indeed, the possibility of establishing a link between optical spectroscopic properties of a given system and the reconstruction of its 3D structure and composition by atom probe tomography yields an unprecedented insight into the complex influence of the structure on the electronic states and on the optical transitions characterizing the system. This lecture will therefore revise the different approaches by which it is possible to correlate optical spectroscopy experiments -in particular micro-photoluminescence with atom probe tomography and, possibly, with transmission electron microscopy. Dedicated sample preparation protocols and recent case studies will be reported. Finally, a perspective approach will be introduced, in which the same femtosecond laser pulse could be exploited not only for triggering ion evaporation, but also photon emission in situ in the atom probe itself.

show abstract

Visualizing highly localized luminescence in GaN/AlN heterostructures in nanowires

Cited by 31 publications

References 51 publications

Localization and defects in axial (In,Ga)N/GaN nanowire heterostructures investigated by spatially resolved luminescence spectroscopy

Localization and defects in axial (In,Ga)N/GaN nanowire heterostructures investigated by spatially resolved luminescence spectroscopy

Nanometer-scale monitoring of quantum-confined Stark effect and emission efficiency droop in multiple GaN/AlN quantum disks in nanowires

Correlative Optical Spectroscopy and Atom Probe Tomography

Contact Info

Product

Resources

About