Deep-Ultraviolet Light-Emitting Diodes Fabricated on AlN Substrates Prepared by Hydride Vapor Phase Epitaxy

Kinoshita, Toru; Hironaka, Keiichiro; Obata, Toshiyuki; Nagashima, Toru; Dalmau, Rafael; Schlesser, R.; Moody, Baxter; Xie, Jinqiao; Inoue, Shin‐ichiro; Kumagai, Yoshinao; Koukitu, Akinori; Sitar, Zlatko

doi:10.1143/apex.5.122101

Cited by 127 publications

(89 citation statements)

References 21 publications

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“…AlN substrate fabrication by hydride vapor-phase epitaxy (HVPE) can significantly reduce the optical absorption when compared with that of typical AlN substrates fabricated by physical vapor transport (PVT) with an absorption coefficient of 35 cm À1 , 7 but HVPE-AlN substrates still show inescapable absorption losses, with an absorption coefficient of approximately 10 cm À1 at a wavelength of approximately 265 nm. 10 Therefore, a trade-off exists between the dislocation density and light extraction. Additionally, early power saturation (i.e., efficiency droop) at high injection current densities is a common problem in flip-chip mesa-type DUVLEDs.…”

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confidence: 99%

“…The MOCVD, HVPE, and LED processing techniques have been described in detail elsewhere. 9,10,13 From bottom to top, the LED structures are composed of a 100-nm-thick AlN homoepitaxial layer, a 1-lm-thick Si-doped n-Al 0.75 Ga 0.25 N layer, three multiple quantum well (MQW) active layers, a Mg-doped p-AlN electron blocking layer, a p-Al 0.8 Ga 0.2 N cladding layer, and a p-GaN contact layer. We enlarged the emitting area to enhance the output power by reducing the current density.…”

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confidence: 99%

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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

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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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confidence: 99%

mentioning

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

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181

118

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“…By using HVPE-AlN as a substrate for growth and subsequent removal of it by mechanical polish, an output power of 28 mW and an EQE of 2.4% were obtained at an injection current of 250 mA in 268 nm DUV LEDs. [55] In another study, TDD in 261 nm DUV LED heterostructures (except the p-GaN layer) grown on HVPE-AlN/PVT-AlN substrates was found to be below 10 6 cm -2 from transmission electron microscopy (TEM) analysis. The lifetime of these LEDs was estimated to be over 10,000 h for CW operation at 50 mA, and over 5,000 h for CW operation at 150 mA.…”

Section: Growth and Optical Properties Of Bulk Aln For Duv Ledsmentioning

confidence: 97%

“…To avoid this, pseudomorphic growth of high Al-molar fraction AlGaN with compressive strain on AlN has been developed. [55,83,84] Because almost no new defects are generated in the pseudomorphic region, the crystalline quality of the AlGaN-based heterostructures becomes comparable to the starting substrate.…”

Section: Pseudomorphic Growth Of High Al-molar Fraction Algan On Alnmentioning

confidence: 99%

Status of Growth of Group III-Nitride Heterostructures for Deep Ultraviolet Light-Emitting Diodes

Ding¹,

Avrutin²,

Özgür³

et al. 2017

Preprint

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Abstract:We overview recent progress in growth aspects of group III-nitride heterostructures for deep ultraviolet (DUV) light-emitting diodes (LEDs), with particular emphasis on the growth approaches for attaining high-quality AlN and high Al-molar fraction AlGaN. The discussion commences with the introduction of the current status of group III-nitride DUV LEDs and the remaining challenges. This segues into discussion of LED designs enabling high device performance followed by the review of advances in the methods for the growth of bulk single crystal AlN intended as a native substrate together with a discussion of its UV transparency. It should be stated, however, that due to the high-cost of bulk AlN substrates at the time of this writing, the growth of DUV LEDs on foreign substrates such as sapphire still dominates the field. On the deposition front, the heteroepitaxial growth approaches incorporate high-temperature metal organic chemical vapor deposition (MOCVD) and pulsed-flow growth, a variant of MOCVD, with the overarching goal of enhancing adatom surface mobility, and thus epitaxial lateral overgrowth which culminates in minimization the effect of lattice-and thermal-mismatches. This is followed by addressing the benefits of pseudomorphic growth of strained high Al-molar fraction AlGaN on AlN. Finally, methods utilized to enhance both p-and n-type conductivity of high Al-molar fraction AlGaN are reviewed.

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“…Furthermore, AlN has promising applications in surface acoustic wave devices (SAW) and microelectromechanical systems (MEMS) due to its high acoustic velocity and piezoelectric properties [2], which are maintained at high temperatures [3,4]. The most attractive perspective for AlN-base devices is in the field of deep-ultraviolet light-emitting diodes working at extremely short wavelengths [5]. For this last application, the most serious challenge is the reduction of defect density in thin films grown on foreign substrates, which limits both efficiency and reliability of the devices [6,7].…”

Section: Introductionmentioning

confidence: 99%

Epitaxial Growth of AlN on (0001) Sapphire: Assessment of HVPE Process by a Design of Experiments Approach

et al. 2017

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Abstract:This study aims to present the interest of using a design of experiments (DOE) approach for assessing, understanding and improving the hydride vapor phase epitaxy (HVPE) process, a particular class of chemical vapor deposition (CVD) process. The case of the HVPE epitaxial growth of AlN on (0001) sapphire will illustrate this approach. The study proposes the assessment of the influence of 15 process parameters on the quality or desired properties of the grown layers measured by 9 responses. The general method used is a screening design with the Hadamard matrix of order 16. For the first time in the growth of AlN by CVD, a reliable estimation of errors is proposed on the measured responses. This study demonstrates that uncontrolled release of condensed species from the cold wall is the main drawback of this process, explaining many properties of the grown layers that could be mistakenly attributed to other phenomena without the use of a DOE. It appears also that the size of nucleation islands, and its corollary, the stress state of the layer at room temperature, are key points. They are strongly correlated to the crystal quality. Due to the intrinsic limitations of the screening design, the complete optimization of responses cannot be proposed but general guidelines for hydride (or halogen) vapor phase epitaxy (HVPE) experimentations, in particular with cold wall apparatus, are given.

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Deep-Ultraviolet Light-Emitting Diodes Fabricated on AlN Substrates Prepared by Hydride Vapor Phase Epitaxy

Cited by 127 publications

References 21 publications

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

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

Status of Growth of Group III-Nitride Heterostructures for Deep Ultraviolet Light-Emitting Diodes

Epitaxial Growth of AlN on (0001) Sapphire: Assessment of HVPE Process by a Design of Experiments Approach

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