Growth of high-quality and crack free AlN layers on sapphire substrate by multi-growth mode modification

Okada, Narihito; Kato, N.; Sato, Shimio; Sumii, T.; Nagai, Takeharu; Fujimoto, Naoki; Imura, Masataka; Balakrishnan, Kalpana; Iwaya, Motoaki; Kamiyama, Satoshi; Amano, Hiroshi; Akasaki, Isamu; Maruyama, Hiroyuki; Takagi, T.; Noro, T.; Bandoh, Akira

doi:10.1016/j.jcrysgro.2006.10.123

Cited by 76 publications

(54 citation statements)

References 6 publications

(8 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…16,17 However, it was also observed that the LT nucleation layer was less effective for the growth of highquality AlGaN than for GaN. 18 Unlike trimethylgallium (TMGa) used in GaN growth, trimethylaluminum (TMAl) used in AlGaN growth has a much stronger pre-reaction with ammonia (NH 3 ) and Al atoms do not have enough time to move to energetically favorable lattice sites due to their low surface mobility. Therefore, three-dimensional islands form more probably than smooth two-dimensional AlGaN.…”

Section: Growth Of High-crystal-quality Algan Epilayersmentioning

confidence: 99%

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.

View full text Add to dashboard Cite

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...

show abstract

Section: Growth Of High-crystal-quality Algan Epilayersmentioning

confidence: 99%

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.

View full text Add to dashboard Cite

show abstract

“…Небольшие островки, преобладающие на началь-ных этапах роста, поглощаются более крупными островками с образованием дислокационных петель, что в конечном итоге приводит к планарному росту (2D) [5]. Этот подход был применен при формировании образца 3.…”

Section: результаты и их обсуждениеunclassified

“…Они ухудшают структурное совер-шенство материала и существенно снижают скорость роста [4]. Пред-ложен ряд подходов, позволяющих в той или иной степени устранить перечисленные выше недостатки [5][6][7]. В основном эти подходы свя-заны с подбором оптимальных на-чальных условий и режимов роста, а также с использованием различных буферных слоев.…”

Section: Introductionunclassified

“…Для исследований зависимости физико химических свойств металлоргани-ческих полимерных нанокомпозитов от технологических параметров их получения предлагается исполь-зовать QSPR (quantitative structure property relationship) модель [4,5] с применением метода наименьших…”

Section: Introductionunclassified

See 1 more Smart Citation

Influence of Conditions of Growth on Structural Perfection of Layers of Aln Received by Method Mos-Gidridnoy of an Epitaxy

Мазалов¹,

Сабитов²,

Курешов³

et al. 2015

Izv. vysš. učebn. zaved., Mater. èlektron. teh.

View full text Add to dashboard Cite

“…A high-quality aluminum nitride (AlN) layer is strongly desired in UV devices due to its wide band gap [1] and in GaN-based transistor structures as a buffer layer [2,3]. Sapphire is one of the most popular substrates for AlN epitaxy because of its wide availability, low cost, and stability at high temperatures.…”

Section: Introductionmentioning

confidence: 99%

The influence of thickness and ammonia flow rate on the properties of AlN layers

Çörekçí

Öztürk

Çakmak

et al. 2012

Materials Science in Semiconductor Processing

View full text Add to dashboard Cite

a b s t r a c tUndoped AlN layers have been grown on c-plane sapphire substrates by metal-organic chemical vapor deposition in order to study the effects of ammonia (NH 3 ) flow rate and layer thickness on the structural quality and surface morphology of AlN layers by highresolution X-ray diffraction, scanning electron microscopy, and atomic force microscopy. Lower NH 3 flow rate improves crystallinity of the symmetric (0 0 0 2) plane in AlN layers. Ammonia flow rate is also correlated with surface quality; pit-free and smooth AlN surfaces have been obtained at a flow rate of 70 standard cm 3 per minute.Thicker AlN films improve the crystallinity of the asymmetric (1 0 1 2) plane.

show abstract

Growth of high-quality and crack free AlN layers on sapphire substrate by multi-growth mode modification

Cited by 76 publications

References 6 publications

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

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

Influence of Conditions of Growth on Structural Perfection of Layers of Aln Received by Method Mos-Gidridnoy of an Epitaxy

The influence of thickness and ammonia flow rate on the properties of AlN layers

Contact Info

Product

Resources

About