Internal quantum efficiency of nitride light emitters: a critical perspective

Hangleiter, A.; Langer, Torsten; Henning, Philipp; Ketzer, Fedor Alexej; Bremers, Heiko; Rossów, U.

doi:10.1117/12.2290082

Cited by 7 publications

(9 citation statements)

References 14 publications

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“…[30][31][32][33] For other samples, as the number of SL periods is reduced the high-temperature effective lifetimes decrease due to thermal activation of defect-assisted recombination. 34,35 The difference in IQE between the samples can be quantified with a simple treatment comparing the initial TRPL decay curve intensity to the effective lifetime (supplementary Sec. III).…”

Section: Resultsmentioning

confidence: 99%

“…Such non-radiative recombination at low temperatures has previously been explained through tunneling-assisted transitions to defect levels. 35 With the improved spatial resolution of under 90 nm at this temperature (supplementary Sec. II), we can be confident we are observing individual PDs as long as densities remain below 10 17 cm −3 .…”

Section: Resultsmentioning

confidence: 99%

“…This efficiency improvement is underscored by the striking contrast in QW effective lifetimes, gained from fitting time-resolved PL (TRPL) decay curves at early delays (Figure d) (see SI Section 4). The lifetime behavior of P24 indicates it is dominated by radiative recombination across the full temperature range, since it exactly matches radiative lifetime behavior in an ideal QW. − For other samples, as the number of SL periods is reduced the high-temperature effective lifetimes decrease due to thermal activation of defect-assisted recombination. , We quantify the IQE of all samples with a simple treatment comparing the initial TRPL intensity to the effective lifetime (SI Section 4). Results are displayed in Figure e: as expected, P24 maintains a high IQE of 64 ± 3% at room temperature, which matches that measured for a similar sample in another study .…”

mentioning

confidence: 94%

“…26−29 For other samples, as the number of SL periods is reduced the high-temperature effective lifetimes decrease due to thermal activation of defect-assisted recombination. 5,30 We quantify the IQE of all samples with a simple treatment comparing the initial TRPL intensity to the effective lifetime (SI Section 4). 31 Results are displayed in Figure 1e: as expected, P24 maintains a high IQE of 64 ± 3% at room temperature, which matches that measured for a similar sample in another study.…”

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confidence: 99%

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Imaging Nonradiative Point Defects Buried in Quantum Wells Using Cathodoluminescence

et al. 2021

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Crystallographic point defects (PDs) can dramatically decrease the efficiency of optoelectronic semiconductor devices, many of which are based on quantum well (QW) heterostructures. However, spatially resolving individual nonradiative PDs buried in such QWs has so far not been demonstrated. Here, using high-resolution cathodoluminescence (CL) and a specific sample design, we spatially resolve, image, and analyze nonradiative PDs in InGaN/GaN QWs at the nanoscale. We identify two different types of PDs by their contrasting behavior with temperature and measure their densities from 10 14 cm −3 to as high as 10 16 cm −3 . Our CL images clearly illustrate the interplay between PDs and carrier dynamics in the well: increasing PD concentration severely limits carrier diffusion lengths, while a higher carrier density suppresses the nonradiative behavior of PDs. The results in this study are readily interpreted directly from CL images and represent a significant advancement in nanoscale PD analysis.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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confidence: 94%

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confidence: 99%

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Imaging Nonradiative Point Defects Buried in Quantum Wells Using Cathodoluminescence

et al. 2021

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“…QW structures with such an indium-free underlayer grown on the c-plane achieve 80%-90% internal quantum efficiency (IQE) at room temperature. 36 Furthermore, Haller et al observe no additional reduction of the nonradiative recombination for AlInN layer thicknesses above 50 nm. 34,35 In contrast, in the present work, a reduction of the nonradiative recombination is observed when the AlInN layer thickness is changed by several hundreds of nanometers, which goes along with a significant reduction of the strain in the QW structure.…”

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confidence: 97%

Reduced nonradiative recombination in semipolar green-emitting III-N quantum wells with strain-reducing AlInN buffer layers

Henning

Horenburg

Bremers

et al. 2019

Applied Physics Letters

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Using strain-reducing partially relaxed AlInN buffer layers, we observe reduced nonradiative recombination in semipolar green-emitting GaInN/GaN quantum wells. Since strain is a key issue for the formation of defects that act as nonradiative recombination centers, we aim to reduce the lattice mismatch between GaInN and GaN by introducing an AlInN buffer layer that can be grown lattice-matched along one of the in-plane directions of GaN, even in the semipolar ð11 22Þ orientation. With the increasing thickness, the buffer layer shows partial relaxation in one direction and thereby provides a growth template with reduced lattice mismatch for the subsequent GaInN quantum wells. Timeresolved photoluminescence measurements show reduced nonradiative recombination for the structures with a strain-reducing buffer layer.

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Influence of Shape and Size on GaN/InGaN μLED Light Emission: A Competition between Sidewall Defects and Light Extraction Efficiency

González-Izquierdo,

Rochat,

Zoccarato

et al. 2023

ACS Photonics

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Micro light-emitting diodes (μLEDs) are expected to revolutionize the display technology due to their advantages over the current LCD and OLED technology and the possibility to use them in micro displays, visible light communications, and optogenetics. One of the main challenges of this emergent technology is the efficiency drop with the reduction of LED size due to sidewall defects. In this article, we study the size and shape dependence of the external quantum efficiency by cathodoluminescence measurements at room temperature and 10 K. Our results show that, for small μLEDs (between 2.5 and 10 μm width), there is an optimal intermediate LED size for which the light emission is maximized, which we attribute to a competition between the light extraction efficiency (LEE) (which decreases with LED size) and the internal quantum efficiency (IQE) (which increases with LED size). In contrast to most prior studies that typically examine either the IQE or LEE with respect to size for larger LEDs, our work stands out by examining the interplay between IQE and LEE for μLEDs below 10 μm. These results are of high relevance for the design of μLED arrays and show the need for understanding the evolution of LEE and sidewall nonradiative recombination with LED geometry and size.

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Internal quantum efficiency of nitride light emitters: a critical perspective

Cited by 7 publications

References 14 publications

Imaging Nonradiative Point Defects Buried in Quantum Wells Using Cathodoluminescence

Imaging Nonradiative Point Defects Buried in Quantum Wells Using Cathodoluminescence

Reduced nonradiative recombination in semipolar green-emitting III-N quantum wells with strain-reducing AlInN buffer layers

Influence of Shape and Size on GaN/InGaN μLED Light Emission: A Competition between Sidewall Defects and Light Extraction Efficiency

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