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Article

UVB LEDs Grown by Molecular Beam Epitaxy Using AlGaN Quantum Dots

1
French National Centre for Scientific Research, Université Côte d’Azur, CEDEX 2, 06108 Nice, France
2
Laboratoire Charles Coulomb and Université Montpellier 2, UMR 5221, 34095 Montpellier, France
*
Author to whom correspondence should be addressed.
Crystals 2020, 10(12), 1097; https://doi.org/10.3390/cryst10121097
Received: 11 November 2020 / Revised: 23 November 2020 / Accepted: 28 November 2020 / Published: 30 November 2020
(This article belongs to the Special Issue Nitride Compound Light Emitting Diodes)
AlGaN based light emitting diodes (LEDs) will play a key role for the development of applications in the ultra-violet (UV). In the UVB region (280–320 nm), phototherapy and plant lighting are among the targeted uses. However, UVB LED performances still need to be improved to reach commercial markets. In particular, the design and the fabrication process of the active region are central elements that affect the LED internal quantum efficiency (IQE). We propose the use of nanometer-sized epitaxial islands (i.e., so called quantum dots (QDs)) to enhance the carrier localization and improve the IQE of molecular beam epitaxy (MBE) grown UVB LEDs using sapphire substrates with thin sub-µm AlN templates. Taking advantage of the epitaxial stress, AlGaN QDs with nanometer-sized (≤10 nm) lateral and vertical dimensions have been grown by MBE. The IQE of the QDs has been deduced from temperature dependent and time resolved photoluminescence measurements. Room temperature IQE values around 5 to 10% have been found in the 290–320 nm range. QD-based UVB LEDs were then fabricated and characterized by electrical and electroluminescence measurements. On-wafer measurements showed optical powers up to 0.25 mW with external quantum efficiency (EQE) values around 0.1% in the 305–320 nm range. View Full-Text
Keywords: light emitting diodes; ultra-violet emission; molecular beam epitaxy; AlGaN; quantum dots; internal quantum efficiency; external quantum efficiency light emitting diodes; ultra-violet emission; molecular beam epitaxy; AlGaN; quantum dots; internal quantum efficiency; external quantum efficiency
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MDPI and ACS Style

Brault, J.; Khalfioui, M.A.; Matta, S.; Ngo, T.H.; Chenot, S.; Leroux, M.; Valvin, P.; Gil, B. UVB LEDs Grown by Molecular Beam Epitaxy Using AlGaN Quantum Dots. Crystals 2020, 10, 1097. https://doi.org/10.3390/cryst10121097

AMA Style

Brault J, Khalfioui MA, Matta S, Ngo TH, Chenot S, Leroux M, Valvin P, Gil B. UVB LEDs Grown by Molecular Beam Epitaxy Using AlGaN Quantum Dots. Crystals. 2020; 10(12):1097. https://doi.org/10.3390/cryst10121097

Chicago/Turabian Style

Brault, Julien, Mohamed A. Khalfioui, Samuel Matta, Thi H. Ngo, Sébastien Chenot, Mathieu Leroux, Pierre Valvin, and Bernard Gil. 2020. "UVB LEDs Grown by Molecular Beam Epitaxy Using AlGaN Quantum Dots" Crystals 10, no. 12: 1097. https://doi.org/10.3390/cryst10121097

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