Efficiency droop in 245–247 nm AlGaN light-emitting diodes with continuous wave 2 mW output power

Sun, Wenhong; Shatalov, M.; Deng, Jixian; Hu, X.; Yang, Jinwei; Lunev, A. V.; Bilenko, Yuri; Shur, M. S.; Gaška, R.

doi:10.1063/1.3302466

Cited by 109 publications

(65 citation statements)

References 14 publications

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“…Reducing "Al" composition in p-type Al Ga N layers to ensure higher conductivity is not an appealing option because it limits critical property like optical confinement. To lase at nm, it is essential to have at least 50% "Al" (or more) in the QWs [9]. The p-type conductivity considerations make it difficult to design symmetric waveguides which keep the optical mode profile centered around the active region and simultaneously afford the design of an efficient EBL to prevent leakage of electrons from the active region.…”

Section: Resultsmentioning

confidence: 99%

Polarization Matching in AlGaN-Based Multiple-Quantum-Well Deep Ultraviolet Laser Diodes on AlN Substrates Using Quaternary AlInGaN Barriers

Satter

Lochner

Ryou

et al. 2012

J. Lightwave Technol.

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A prototypical design of AlGaN deep ultraviolet (DUV) laser diodes (LDs) on AlN substrates employing tapered electron blocking layer is presented. Two-dimensional optoelectronic simulation predicts lasing at a target wavelength of 250 nm. Degradation of optical gain associated with spatial separation of electron and hole wave functions inside the active region may be considerably reduced in designs featuring quaternary AlInGaN barriers, by virtue of polarization charge matching. A systematic method for selection of polarization-free quaternary barrier compositions is proposed for 250 nm DUV LD designs, accompanied by a sensitivity analysis. The selection procedure presented here is readily applied to LDs and light-emitting diodes operating at other wavelengths.Index Terms-AlN substrate, AlGaN active layer, deep ultraviolet (DUV) laser diodes (LDs), polarization charge, quantum-confined Stark effect (QCSE), quaternary barrier, tapered electron blocking layer (EBL).

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Section: Resultsmentioning

confidence: 99%

Polarization Matching in AlGaN-Based Multiple-Quantum-Well Deep Ultraviolet Laser Diodes on AlN Substrates Using Quaternary AlInGaN Barriers

Satter

Lochner

Ryou

et al. 2012

J. Lightwave Technol.

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“…Additionally, early power saturation (i.e., efficiency droop) at high injection current densities is a common problem in flip-chip mesa-type DUVLEDs. 11,12 Therefore, to achieve both high reliability and high power operation, it is essential to enlarge the light escape cones of flip-chip DUV-LEDs on AlN substrates to minimize optical absorption while simultaneously expanding the emitting area to allow higher current operation and increased output flux per single chip LED. In this letter, we report on the design and large-area fabrication of sub-270 nm AlGaN-based flip-chip DUV-LEDs on AlN substrates with light-extraction structures to improve the LED output power.…”

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confidence: 99%

150 mW deep-ultraviolet light-emitting diodes with large-area AlN nanophotonic light-extraction structure emitting at 265 nm

Inoue

Tamari

Taniguchi

2017

Applied Physics Letters

174

118

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High-power 265 nm deep-ultraviolet (DUV) AlGaN-based light-emitting diodes (LEDs) with large-area AlN nanophotonic light-extraction structures that were fabricated by a nanoimprint lithography process are presented. Each DUV-LED has a large active area (mesa size of ∼0.35 mm2) and a uniform current spreading design that allows high injection current operation. We have shown that these DUV-LEDs with their large-area nanoimprinted AlN nanophotonic structures exhibit wider near-field emitting areas, stronger far-field extracted light intensities, and an approximately 20-fold increase in output power when compared with a conventional flat-surface DUV-LED. A large-area nanoimprinted single-chip DUV-LED operating in the UV-C wavelength regime has demonstrated a record continuous-wave output power in excess of 150 mW for an injection current of 850 mA at a peak emission wavelength of 265 nm.

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“…The efficiency droop has also been observed in AlGaN materials used for the UV LEDs [10][11][12]. In this report, we study the droop behavior in high-Al-content AlGaN/AlGaN MQW structures.…”

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confidence: 81%

Efficiency droop in high‐Al‐content AlGaN/AlGaN quantum wells

Тамулайтис

Mickevičius

Kazlauskas

et al. 2011

Phys. Status Solidi C

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Excitation power density dependence of photoluminescence (PL) efficiency is studied in the temperature range from 8 to 300 K for AlGaN multiple quantum well structures containing quantum wells of different width. PL efficiency droop is observed and dependence of the droop effect on the well width and lattice temperature is discussed. Photoluminescence band shape reveals strong carrier heating. It is shown that the heating effect has a substantial influence on the photoluminescence efficiency droop, especially at low lattice temperatures. Fitting of the temperature dependence of the PL band width with that obtained by the Monte Carlo simulation of carrier (exciton) hopping via localized states shows that (i) the potential fluctuations can be fairly accurately described using a double‐scaled potential profile model, (ii) the localization becomes stronger in narrower quantum wells. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Efficiency droop in 245–247 nm AlGaN light-emitting diodes with continuous wave 2 mW output power

Cited by 109 publications

References 14 publications

Polarization Matching in AlGaN-Based Multiple-Quantum-Well Deep Ultraviolet Laser Diodes on AlN Substrates Using Quaternary AlInGaN Barriers

Polarization Matching in AlGaN-Based Multiple-Quantum-Well Deep Ultraviolet Laser Diodes on AlN Substrates Using Quaternary AlInGaN Barriers

150 mW deep-ultraviolet light-emitting diodes with large-area AlN nanophotonic light-extraction structure emitting at 265 nm

Efficiency droop in high‐Al‐content AlGaN/AlGaN quantum wells

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