Deep Ultraviolet AlGaInN-Based Light-Emitting Diodes on Si(111) and Sapphire

Kipshidze, G.; Kuryatkov, V.; Borisov, B.; Nikishin, S. A.; Holtz, M.; Chu, Sheng; Temkin, H.

doi:10.1002/1521-396x(200208)192:2<286::aid-pssa286>3.0.co;2-2

Cited by 36 publications

(48 citation statements)

References 16 publications

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“…In contrast, the excitation capabilities of photoluminescence (PL) are limited by the incident photon energy [54][55][56]. As a result, it is easier to study deep UV emission with CL than PL [57][58][59][60]. In addition, whereas one incident photon can generate not more than one e-h pair, one incident electron of energy E produces ∼E/3E g pairs, where E g is the band gap of the material [3,4], i.e.…”

Section: Strong Excitationmentioning

confidence: 99%

Low-energy cathodoluminescence microscopy for the characterization of nanostructures

Dierre

Yuan

Sekiguchi

2010

Science and Technology of Advanced Materials

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Spatially and spectrally resolved low-energy cathodoluminescence (CL) microscopy was applied to the characterization of nanostructures. CL has the advantage of revealing not only the presence of luminescence centers but also their spatial distribution. The use of electrons as an excitation source allows a direct comparison with other electron-beam techniques. Thus, CL is a powerful method to correlate luminescence with the sample structure and to clarify the origin of the luminescence. However, caution is needed in the quantitative analysis of CL measurements. In this review, the advantages of cathodoluminescence for qualitative analysis and disadvantages for quantitative analysis are presented on the example of nanostructures.

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Section: Strong Excitationmentioning

confidence: 99%

Low-energy cathodoluminescence microscopy for the characterization of nanostructures

Dierre

Yuan

Sekiguchi

2010

Science and Technology of Advanced Materials

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“…Thus, various methods have been developed, including p-GaN contact layer [117][118][119][120] and superlattice structures, 38,[121][122][123][124][125][126][127][128][129][130] in order to achieve efficient current injection into Al-rich p-Al x Ga 1-x N.…”

Section: 99mentioning

confidence: 91%

Review—Group III-Nitride-Based Ultraviolet Light-Emitting Diodes: Ways of Increasing External Quantum Efficiency

Park

Kim

Cho

et al. 2017

ECS J. Solid State Sci. Technol.

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There is a rapidly growing demand for highly efficient ultraviolet (UV) light sources for a wide variety of applications. In particular, state-of-the-art AlGaN deep UV light-emitting diodes (DUV LEDs) exhibit inadequately low external quantum efficiencies (EQEs). The low efficiencies are attributed to the inherent material properties of high-Al-content AlGaN including strained epitaxial layers, low carrier concentrations, and strong transverse magnetic (TM)-polarized light emission. Extensive efforts have been made to tackle these challenging issues and technological developments have been achieved and enabled the fabrication of reasonable EQE LEDs. In this review, recent advances in the growth of high-quality AlGaN epitaxial layers, transparent and reflective ohmic contacts, and light extraction for AlGaN-based UV LEDs are reviewed. Al x Ga 1-x N-based ultraviolet light-emitting diodes (UV LEDs) are of technological importance because of their applications in numerous areas such as water purification, biological analysis, sensing, epoxy curing, high-density optical storage, white light illumination, UV adhesives, 3-dimensional (3D) printer and UV-coating.1,2 These applications are made possible because of their wide bandgap energy range in the UV spectrum, which spans from 6.2 eV (AlN) to 3.4 eV (GaN), namely, from UV-A (320-400 nm), UV-B (290-320 nm) to UV-C (200-290 nm).3-7 The external quantum efficiency (EQE) of Al x Ga 1-x N-based UV LEDs decreases rapidly as the molar fraction (x) of Al increases, namely, as the wavelength decreases, as illustrated in Figure 1. 8 Thus, a great deal of effort has been made in order to improve the EQE of UV LEDs. The effort notwithstanding, however, the EQE of AlGaN-based UV LEDs is still insufficiently low. The typical EQE of UV LEDs, specifically in the UV-C spectral range (100-280 nm), is less than 5% and decreases down to 10 -6 % for 210-nm AlN-based UV LEDs. 4 These low EQEs are associated with the intrinsic material properties of Al x Ga 1-x N.1,2 Figure 2 exhibits a schematic diagram of a typical AlGaN UV LED structure grown on a sapphire substrate. The structure consists of a Si-doped n-type AlGaN, an Al x Ga 1-x N/Al y Ga 1-y N multiple-quantum well (MQW) active region, an AlGaN-based electron-blocking layer (EBL), a Mg-doped p-type AlGaN, and a Mg-doped p-type GaN. Almost every layer in the structure poses different technical issues, which limit the efficiency of UV LEDs, as shown in Figure 2. First, increasing the Al content generally results in a poor crystallinity of AlGaN epilayers, causing a poor internal quantum efficiency (IQE). Second, both n-type and ptype doping efficiencies of AlGaN are difficult to increase because the ionization energies of acceptor (Mg) and donor (Si) dopants largely increase with increasing Al content. The low doping efficiency causes several technological problems: (i) a poor electrical efficiency (EE) attributable to high-resistance contacts on resistive n-type and p-type AlGaN; (ii) current crowding causing non-uniform current in...

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“…To date, most of the work on III-nitride UV photodetectors, inclusive of all types, has relied on bulk-like epilayers. Kipshidze et al [14] reported GaN/ AlGaN MQW in an effort to extend the range of wavelength in LED [18]. As for infrared detectors, other III-V material systems, such as GaAs or InP based, devices containing MQWs in their active region have been successfully designed and demonstrated [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

GaN/AlGaN back-illuminated multiple-quantum-well Schottky barrier ultraviolet photodetectors

Teke

Doğan

Yun

et al. 2003

Solid-State Electronics

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We report on characterization and operation principle of a set of GaN/AlGaN multiple-quantum-well (MQW) photovoltaic detectors. The structures were grown by molecular beam epitaxy (MBE) on c-plane sapphire substrates and fabricated in the back-illuminated vertical Schottky geometry. Introduction of MQWs into the active region of devices is expected to enhance the quantum efficiency due to the high absorption coefficient. A nearly flat spectral responsivity between 325 and 350 nm with 0.054 A/W peak responsivity was achieved from the single-side polished backside (rough) illuminated GaN/AlGaN MQW devices. The cutoff wavelength of the MQW photodetector can be tuned by adjusting the well width, well composition and barrier height. A model has been developed to gain insight into the operation principles of MQWs photodiodes. The peak responsivity increased with decreasing barrier thickness due to enhanced tunneling of photogenerated carriers.

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Deep Ultraviolet AlGaInN-Based Light-Emitting Diodes on Si(111) and Sapphire

Cited by 36 publications

References 16 publications

Low-energy cathodoluminescence microscopy for the characterization of nanostructures

Low-energy cathodoluminescence microscopy for the characterization of nanostructures

Review—Group III-Nitride-Based Ultraviolet Light-Emitting Diodes: Ways of Increasing External Quantum Efficiency

GaN/AlGaN back-illuminated multiple-quantum-well Schottky barrier ultraviolet photodetectors

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