Microstructural origins of localization in InGaN quantum wells

Oliver, Rachel A.; Bennett, S. E.; Zhu, Tongtong; Beesley, David; Kappers, Menno J.; Saxey, David W.; Cerezo, A.; Humphreys, C. J.

doi:10.1088/0022-3727/43/35/354003

Cited by 85 publications

(67 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Along this line, Kehagias et al [11] have shown that for lower growth temperatures of the (In,Ga)N insertions, the inhomogeneity of the alloy is further increased and the width of the (In,Ga)N band for the NW ensemble can amount to 800 meV. A certain degree of localization might well be necessary to avoid the possibility of detrimental carrier recombination at the NW surface in line with what is discussed for dislocations in planar layers [48]. However, strong inhomogeneities impede the desired tunability of emission properties [9].…”

Section: Single Nw Photoluminescencementioning

confidence: 75%

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: Single Nw Photoluminescencementioning

confidence: 75%

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

“…The reason that InGaN LEDs are much more tolerant of TDs than other conventional III-V materials is probably due to carrier localisation effects [20][21][22][23][24][25][26]. The first contributing factor is the monolayer height interface steps on the InGaN quantum wells.…”

Section: à2mentioning

confidence: 99%

Solid-State Lighting Based on Light Emitting Diode Technology

Zhu

Humphreys

2016

Optics in Our Time

View full text Add to dashboard Cite

“…The (a+c)-type cores were studied because they are (a) easier to locate than a-type cores, (b) present in our samples in proportions (in contrast to the pure ctype cores which comprise only ~1% of all dislocations in our samples), (c) they reveal the effects of both a-type and c-type Burgers vectors components and (d) the highest energetic stabilization of In segregation is predicted for this core type and therefore it is most likely to be observed experimentally. for In x Ga 1-x N epilayers 57 , with a side length of approximately 40 nm. Precise identification of the core configuration is not possible due to ambiguous contrast at the core, which could be consistent with a disrupted, rather than highly symmetrical, core configuration consistent with the highly segregated In-rich cores predicted as seen in Figure 3(c).…”

mentioning

confidence: 99%

Segregation of In to Dislocations in InGaN

et al. 2015

View full text Add to dashboard Cite

Dislocations are one-dimensional topological defects which occur frequently in functional thin film materials and which are known to degrade the performance of In x Ga 1-x N-based optoelectronic devices. Here, we show that large local deviations in alloy composition and atomic structure re expected to occur in and around dislocation cores in In x Ga 1-x N alloy thin 2 films. We present energy-dispersive X-ray spectroscopy data supporting this result. The methods presented here are also widely applicable for predicting composition fluctuations associated with strain fields in other inorganic functional material thin films. KEYWORDSDislocations, III-nitrides, Monte Carlo, alloy segregation, atomistic modeling, STEM-EDX MAIN TEXTDislocations are ubiquitous one-dimensional topological defects that are found within thin films of nitride semiconductors, originating at the interface with the substrate, and threading up through the active region of the device before terminating at the crystal surface 1 . These dislocations can severely degrade device efficiencies 2 , and lifetimes 3 and are responsible for a broad range of undesirable behavior such as leakage currents 4 and properties such as reduced internal quantum efficiencies 5 and defect states 6,7,8,9,10 that can act as non-radiative recombination centers. In x Ga 1-x N-based alloy semiconductors are used in light-emitting diodes 11 , laser diodes 12 and solar cells 13 , which can be tuned to emit or absorb respectively over the entire visible spectrum by varying the In composition 14 . In x Ga 1-x N is subject to very high threading dislocation densities of up to 10 11 cm -2 and typically around 10 9 cm -2 when grown by metalorganic vapourphase epitaxy 15 (MOVPE), of which the majority have a-type ('edge') or (a+c)-type ('mixed') Burgers vectors with < 1% 16 being c-type ('screw'). High dislocation densities are associated with short lifetimes in InGaN-based optoelectronic devices 17 . The electronic properties of dislocations are determined by the local bonding in the region of the dislocation core 8 . It is therefore important to determine whether or not there are local differences in the alloy composition near dislocation cores in In x Ga 1-x N. Such composition fluctuations are likely to 3 affect the electronic properties of the dislocations and would therefore affect device performance.Each dislocation is associated with a strain field determined by its Burgers vector. Since the In atom is larger than the host Ga atom, it is expected that if the In atoms are sufficiently mobile during growth, then they will segregate to the tensile part of the dislocation strain field 18 .Previous theoretical work has shown that the extreme case of a pure InN c-type dislocation core in an In x Ga 1-x N alloy is more energetically favorable compared to the equivalent In x Ga 1-x N core 19 , and also that it is favorable for In atoms to bind to a c-type dislocation core in GaN 20 . Due to the sensitivity required to detect small variations in alloy concentration on sh...

show abstract

Microstructural origins of localization in InGaN quantum wells

Cited by 85 publications

References 47 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

Solid-State Lighting Based on Light Emitting Diode Technology

Segregation of In to Dislocations in InGaN

Contact Info

Product

Resources

About