Low temperature studies of the efficiency droop in InGaN-based light-emitting diodes

Shim, Jong‐In; Kim, Hyunsung; Han, Dong‐Pyo; Shin, Dong‐Soo; Kim, Kyu Sang

doi:10.1117/12.2037986

Cited by 6 publications

(6 citation statements)

References 8 publications

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“…Therefore, the IQE droop can be ascribed to the saturation of the nonradiative recombination rate at low currents, and an increase in the SRH process of the nonradiative recombination rates at high currents. 28 To further investigate the cause of the droop noted in our VLED, we studied the peak energy and the FWHM of the EL peak as a function of the input current. Figure 2d shows that, as the current increases from 50 mA to 160 mA, the peak energy remains relatively constant, with a very slight redshift (~ 8 meV).…”

Section: Resultsmentioning

confidence: 99%

“…No decline in the EL intensity is observed in this injection range, indicating a good performance of the device and suggesting that the Auger recombination is negligible at high carrier injection rates. Therefore, the IQE droop can be ascribed to the saturation of the nonradiative recombination rate at low currents and an increase in the SRH process of the nonradiative recombination rates at high currents …”

Section: Resultsmentioning

confidence: 99%

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High-Efficiency InGaN/GaN Quantum Well-Based Vertical Light-Emitting Diodes Fabricated on β-Ga₂O₃ Substrate

Muhammed

Alwadai

Lopatin

et al. 2017

ACS Appl. Mater. Interfaces

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We demonstrate a state-of-the-art high-efficiency GaN-based vertical light-emitting diode (VLED) grown on a transparent and conductive (-201)-oriented (β-GaO) substrate, obtained using a straightforward growth process that does not require a high-cost lift-off technique or complex fabrication process. The high-resolution scanning transmission electron microscopy (STEM) images confirm that we produced high quality upper layers, including a multiquantum well (MQW) grown on the masked β-GaO substrate. STEM imaging also shows a well-defined MQW without InN diffusion into the barrier. Electroluminescence (EL) measurements at room temperature indicate that we achieved a very high internal quantum efficiency (IQE) of 78%; at lower temperatures, IQE reaches ∼86%. The photoluminescence (PL) and time-resolved PL analysis indicate that, at a high carrier injection density, the emission is dominated by radiative recombination with a negligible Auger effect; no quantum-confined Stark effect is observed. At low temperatures, no efficiency droop is observed at a high carrier injection density, indicating the superior VLED structure obtained without lift-off processing, which is cost-effective for large-scale devices.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

High-Efficiency InGaN/GaN Quantum Well-Based Vertical Light-Emitting Diodes Fabricated on β-Ga₂O₃ Substrate

Muhammed

Alwadai

Lopatin

et al. 2017

ACS Appl. Mater. Interfaces

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“…[53] Therefore, the phonon interaction in the indirect bandgap structure of CsPbI 3 led to a shorter lifetime at RT and a longer lifetime at low temperature compared to those of direct bandgap materials. [57,58]…”

Section: Advanced Optical Analysis and The Band Structurementioning

confidence: 99%

Identifying Carrier Behavior in Ultrathin Indirect‐Bandgap CsPbX₃ Nanocrystal Films for Use in UV/Visible‐Blind High‐Energy Detectors

Xin

Alaal

Mitra

et al. 2020

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and military devices. Among these applications, medical diagnostics is particularly significant, but it presently requires direct exposure to high doses of radiation, which is harmful to human health, increasing cancer risk, especially in children. [1,2] Hence, X-ray detectors possessing both high sensitivity and high resolution with a low light interface noise [3,4] are required to minimize the radiation exposure during routine medical diagnostics. In the pertinent literature, use of conventional semiconductors for direct X-ray detection has been reported by several groups, including amorphous Se, [5] crystalline Si, [6] Ge, [7] HgI 2 , [8] CdTe, [9,10] and CdZnTe, [9,10] indicating that the most effective materials are indirect bandgap semiconductors [5-10] that exhibit low light interference noise. However, as such devices possess low sensitivity due to the low atomic number values of their materials, [7] as well as they still require expensive fabrication and complex processing methods, there is a high industrial demand for cost-effective highly sensitive X-ray detectors that are more suited for mass production. Ionic perovskite crystals can be processed from solution at low temperatures, in contrast to covalent bond semiconductors, which require a high-temperature crystallization process. Consequently, lead halogen perovskite has emerged as a promising candidate due to its cost-effectiveness, high crystal quality, high absorption cross-section, high illumination, and ability to form High-energy radiation detectors such as X-ray detectors with low light photoresponse characteristics are used for several applications including, space, medical, and military devices. Here, an indirect bandgap inorganic perovskite-based X-ray detector is reported. The indirect bandgap nature of perovskite materials is revealed through optical characterizations, time-resolved photoluminescence (TRPL), and theoretical simulations, demonstrating that the differences in temperature-dependent carrier lifetime related to CsPbX 3 (X = Br, I) perovskite composition are due to the changes in the bandgap structure. TRPL, theoretical analyses, and X-ray radiation measurements reveal that the high response of the UV/visible-blind yellow-phase CsPbI 3 under high-energy X-ray exposure is attributed to the nature of the indirect bandgap structure of CsPbX 3. The yellowphase CsPbI 3-based X-ray detector achieves a relatively high sensitivity of 83.6 μCGy air −1 cm −2 (under 1.7 mGy air s −1 at an electron field of 0.17 V μm −1 used for medical diagnostics) although the active layer is based solely on an ultrathin (≈6.6 μm) CsPbI 3 nanocrystal film, exceeding the values obtained for commercial X-ray detectors, and further confirming good material quality. This CsPbX 3 X-ray detector is sufficient for cost-effective device miniaturization based on a simple design.

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“…The results from the TEM, TDPL, and TRPL evidence that carrier localization caused by In clustering is absent, leading to a uniform carrier distribution in high-quality Qdisks, hence increasing the effective active volume in InGaN Qdisks . Ultimately, the saturation of the radiative recombination rate is suppressed, and at RT or above this is not limited by SRH nonradiative recombination, Auger recombination, or carrier leakage, thus realizing droop-free operation.…”

mentioning

confidence: 95%

“…However, the application of nitride light-emitting diodes (LEDs) is limited by their decreased efficiency at the peak sensitivity of human photopic vision spectrum, termed the “green gap” . Moreover, the high dislocation density of the materials, together with efficiency droop phenomenon of LEDs at high current injection also hinder their high-brightness applications, which was attributed to the saturation of the radiative recombination rate and increase in the nonradiative recombination rate, such as Shockley–Read–Hall (SRH) nonradiative recombination, Auger recombination, and electron leakage. , Compared to conventional planar devices, III-nitride nanowire devices have attractive advantages, such as dislocation- and strain-free materials, a reduced polarization field, and enhanced carrier confinement. , Nanowire devices on silicon have been investigated for application in LEDs and lasers. , …”

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confidence: 99%

Droop-Free, Reliable, and High-Power InGaN/GaN Nanowire Light-Emitting Diodes for Monolithic Metal-Optoelectronics

et al. 2016

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A droop-free nitride light-emitting diode (LED) with the capacity to operate beyond the "green gap" has been a subject of intense scientific and engineering interest. While several properties of nanowires on silicon make them promising for use in LED development, the high aspect ratio of individual nanowires and their laterally discontinuous features limit phonon transport and device performance. Here, we report on the monolithic integration of metal heat-sink and droop-free InGaN/GaN quantum-disks-in-nanowire LEDs emitting at ∼710 nm. The reliable operation of our uncooled nanowire-LEDs (NW-LEDs) epitaxially grown on molybdenum was evident in the constant-current soft burn-in performed on a 380 μm × 380 μm LED. The square LED sustained 600 mA electrical stress over an 8 h period, providing stable light output at maturity without catastrophic failure. The absence of carrier and phonon transport barriers in NW-LEDs was further inferred from current-dependent Raman measurements (up to 700 mA), which revealed the low self-heating. The radiative recombination rates of NW-LEDs between room temperature and 40 °C was not limited by Shockley-Read-Hall recombination, Auger recombination, or carrier leakage mechanisms, thus realizing droop-free operation. The discovery of reliable, droop-free devices constitutes significant progress toward the development of nanowires for practical applications. Our monolithic approach realized a high-performance device that will revolutionize the way high power, low-junction-temperature LED lamps are manufactured for solid-state lighting and for applications in high-temperature harsh environment.

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Low temperature studies of the efficiency droop in InGaN-based light-emitting diodes

Cited by 6 publications

References 8 publications

High-Efficiency InGaN/GaN Quantum Well-Based Vertical Light-Emitting Diodes Fabricated on β-Ga₂O₃ Substrate

High-Efficiency InGaN/GaN Quantum Well-Based Vertical Light-Emitting Diodes Fabricated on β-Ga₂O₃ Substrate

Identifying Carrier Behavior in Ultrathin Indirect‐Bandgap CsPbX₃ Nanocrystal Films for Use in UV/Visible‐Blind High‐Energy Detectors

Droop-Free, Reliable, and High-Power InGaN/GaN Nanowire Light-Emitting Diodes for Monolithic Metal-Optoelectronics

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Low temperature studies of the efficiency droop in InGaN-based light-emitting diodes

Cited by 6 publications

References 8 publications

High-Efficiency InGaN/GaN Quantum Well-Based Vertical Light-Emitting Diodes Fabricated on β-Ga2O3 Substrate

High-Efficiency InGaN/GaN Quantum Well-Based Vertical Light-Emitting Diodes Fabricated on β-Ga2O3 Substrate

Identifying Carrier Behavior in Ultrathin Indirect‐Bandgap CsPbX3 Nanocrystal Films for Use in UV/Visible‐Blind High‐Energy Detectors

Droop-Free, Reliable, and High-Power InGaN/GaN Nanowire Light-Emitting Diodes for Monolithic Metal-Optoelectronics

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Product

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High-Efficiency InGaN/GaN Quantum Well-Based Vertical Light-Emitting Diodes Fabricated on β-Ga₂O₃ Substrate

High-Efficiency InGaN/GaN Quantum Well-Based Vertical Light-Emitting Diodes Fabricated on β-Ga₂O₃ Substrate

Identifying Carrier Behavior in Ultrathin Indirect‐Bandgap CsPbX₃ Nanocrystal Films for Use in UV/Visible‐Blind High‐Energy Detectors