Localization and transient emission properties in InGaN/GaN quantum wells of different polarities within core–shell nanorods

Robin, Yoann; Evropeitsev, E. A.; Shubina, T. V.; Kirilenko, D. A.; Davydov, V. Yu.; Смирнов, А. Н.; Торопов, А. А.; Eliseyev, I. A.; Bae, Si‐Young; Kushimoto, Maki; Nitta, Shugo; Иванов, С. В.; Amano, Hiroshi

doi:10.1039/c8nr05863f

Cited by 10 publications

(7 citation statements)

References 34 publications

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“…Therefore, the spectra exhibit broad emission peak owing to different In fractions on the three different facets. At 21 K, the dominant emission peak in sample b is longer than that at room temperature, as plotted in Figure b, which might be related to the emission from deep level defects in GaN . Assuming that the nonradiative recombination at low temperature is inactivated (IQE = 100%), the IQE at room temperature can be calculated through the ratio of integrated PL intensity measured at room temperature and 21 K (IQE = I RT / I 21K ) .…”

Section: Resultssupporting

confidence: 72%

“…At 21 K, the dominant emission peak in sample b is longer than that at room temperature, as plotted in Figure 4b, which might be related to the emission from deep level defects in GaN. 41 Assuming that the nonradiative recombination at low temperature is inactivated (IQE = 100%), the IQE at room temperature can be calculated through the ratio of integrated PL intensity measured at room temperature and 21 K (IQE = I RT /I 21K ). 42 The estimated IQEs for samples a and c are 38 and 69%, respectively, which is quite consistent with the improvement in CL intensity.…”

Section: Resultsmentioning

confidence: 99%

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Correlation between Optical and Structural Characteristics in Coaxial GaInN/GaN Multiple Quantum Shell Nanowires with AlGaN Spacers

Miyamoto

Okuda

et al. 2020

ACS Appl. Mater. Interfaces

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High crystalline quality coaxial GaInN/GaN multiple quantum shells (MQSs) grown on dislocation-free nanowires are highly in demand for efficient white-/micro-light-emitting diodes (LEDs). Here, we propose an effective approach to improve the MQS quality during the selective growth by metal–organic chemical vapor deposition. By increasing the growth temperature of GaN barriers, the cathodoluminescent intensity yielded enhancements of 0.7 and 3.9 times in the samples with GaN and AlGaN spacers, respectively. Using an AlGaN spacer before increasing the barrier temperature, the decomposition of GaInN quantum wells was suppressed on all planes, resulting in a high internal quantum efficiency up to 69%. As revealed by scanning transmission electron microscopy (STEM) characterization, the high barrier growth temperature allowed to achieve a clear interface between GaInN quantum wells and GaN quantum barriers on the c-, r-, and m-planes of the nanowires. Moreover, the correlation between the In incorporation and structure features in MQS was quantitatively assessed based on the STEM energy-dispersive X-ray spectroscopy mapping and line-scan profiles of In and Al fractions. Ultimately, it was demonstrated that the unintentional In incorporation in GaN barriers was induced by the evaporation of predeposited In-rich particles during low-temperature growth of GaInN wells. Such residual In contamination was sufficiently inhibited by inserting low Al fraction (∼6%) AlGaN spacers after each GaInN well. During the growth of AlGaN spacers, AlN polycrystalline particles were deposited on the surrounding dummy substrate, which suppressed the evaporation of the predeposited In-rich particles. Thus, the presence of AlGaN spacers certainly improved the uniformity of In fraction through five GaInN quantum wells and reduced the diffusion of point defects from n-core to MQS active structures. The superior coaxial GaInN/GaN MQS structures with the AlGaN spacer are supposed to improve the emission efficiency in white-/micro-LEDs.

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Section: Resultssupporting

confidence: 72%

Section: Resultsmentioning

confidence: 99%

Correlation between Optical and Structural Characteristics in Coaxial GaInN/GaN Multiple Quantum Shell Nanowires with AlGaN Spacers

Miyamoto

Okuda

et al. 2020

ACS Appl. Mater. Interfaces

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“…This observation allows us to ascribe the PL peaks at ≈395 and 430–480 nm to the non‐polar and semi‐polar QWs, respectively. Other arguments in favor of this assignment are given in our previous papers …”

Section: Pl Bands and Narrow Peaks Assignmentmentioning

confidence: 90%

“…The diameter and height of the NRs are about 900 and 1600 nm, respectively. The growth conditions and PL kinetics are described in detail in our previous papers . The reference GaN NRs without the InGaN/GaN QWs were grown at the similar conditions as the basic set of core–shell NRs.…”

Section: Experimental Techniquesmentioning

confidence: 99%

Narrow Excitonic Lines in Core–Shell Nanorods With InGaN/GaN Quantum Wells Intersected by Basal Stacking Faults

Evropeitsev

Robin

Shubina

et al. 2019

Physica Status Solidi (b)

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Individual core-shell GaN nanorods (NRs) with InGaN quantum wells (QWs), lying in non-polar, semi-polar, and polar planes, are investigated by micro-photoluminescence (μ-PL) spectroscopy. Complementary transmission electron microscopy (TEM) studies reveal the presence of basal stacking faults (BSFs), which intersect the QWs. Narrow peaks of excitonic emission were detected at the NR tips, where the BSFs can both cross the semi-polar QWs and penetrate through the thick polar well. In the NRs without the polar wells, the peaks appear in the blue spectral range only, while in the NRs with such wells, the peaks also appear in the green spectral range. Polarization resolved μ-PL measurements reveal the scattering of linear polarization degree among the narrow peaks, as well as among individual NRs, although the dominant polarization of the narrow lines was normal to the NR axis. In general, these findings are consistent with the origination of the narrow excitonic lines from the intersections of the BSFs with QWs of different types. Experimental TechniquesThe NRs were grown on a Si-doped GaN template (n ¼ 4 Â 10 18 cm À3 ) formed on a silicon (111) substrate by

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“…6 Similar values (21−35 ps) have been found for polarization-free InGaN/GaN multiquantum wells (MQWs) wires at 300 K. 7,8 In addition, carrier decay rates that deviate from the single-exponential curves were revealed, 9 indicating multiple carrier localization effects present in core−shell InGaN/GaN heterostructures. 10 While ensembles of wires are often investigated by time-resolved photoluminescence (TRPL), 11,12 to date only little attention has been paid to carrier decay rates in single wires using more sophisticated approaches, like time-resolved cathodoluminescence (TRCL) 13 and ultrafast optical microscopy. 14 Alternatively, scanning near-field optical microscopy (SNOM) equipped with a short-pulsed laser 15 and microelectroluminescence through the probe of scanning tunneling microscopy could be used.…”

mentioning

confidence: 99%

Spatially and Time-Resolved Carrier Dynamics in Core–Shell InGaN/GaN Multiple-Quantum Wells on GaN Wire

et al. 2021

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Time-resolved cathodoluminescence is a key tool with high temporal and spatial resolution. However, optical spectroscopic information can be also extracted using synchrotron pulses in a hard X-ray nanoprobe, exploiting a phenomenon called X-ray excited optical luminescence. Here, with 20 ps time resolution and 80 nm lateral resolution, we applied this timeresolved X-ray microscopy technique to individual core−shell InGaN/GaN multiple quantum well heterostructures deposited on GaN wires. Our findings suggest that the m-plane related multiple quantum well states govern the carrier dynamics. Likewise, our observations support not only the influence of In incorporation in the recombination rates, but also carrier localization phenomena at the hexagon wire apex. In addition, our experiment calls for further investigations of the spatiotemporal domain on the underlying mechanisms of optoelectronic nanodevices. Its great potential becomes more valuable when time-resolved X-ray excited optical luminescence microscopy is used in operando with other methods, such as X-ray absorption spectroscopy.

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Localization and transient emission properties in InGaN/GaN quantum wells of different polarities within core–shell nanorods

Abstract: Transient photoluminescence (PL) characteristics and localization phenomena in InGaN/GaN core–shell nanorods (NRs) were investigated from 6 K up to 285 K.

Cited by 10 publications

References 34 publications

Correlation between Optical and Structural Characteristics in Coaxial GaInN/GaN Multiple Quantum Shell Nanowires with AlGaN Spacers

Correlation between Optical and Structural Characteristics in Coaxial GaInN/GaN Multiple Quantum Shell Nanowires with AlGaN Spacers

Narrow Excitonic Lines in Core–Shell Nanorods With InGaN/GaN Quantum Wells Intersected by Basal Stacking Faults

Spatially and Time-Resolved Carrier Dynamics in Core–Shell InGaN/GaN Multiple-Quantum Wells on GaN Wire

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