Impact of AlN nucleation layer on strain in GaN grown on 4H-SiC substrates

Cho, E.; Mogilatenko, A.; Brunner, F.; Richter, E.; Weyers, M.

doi:10.1016/j.jcrysgro.2013.02.001

Cited by 34 publications

(10 citation statements)

References 14 publications

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“…Nevertheless, since the first GaN-on-SiC epitaxy was realized by the use of an AlN interlayer more than two decades ago, there has been limited progress in the epitaxial growth. [4][5][6][7] The AlN interlayers/nucleation layers (NLs) typically exhibit grain-like morphology and then evolve into column-like growth as the thickness increases, due to the low mobility of Al adatoms. Structural defects like voids and dislocations generated at the interfaces of GaN/AlN/SiC introduce a thermal boundary resistance (TBR) that results in an additional 30%-40% channel temperature rise in HEMTs.…”

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confidence: 99%

A GaN–SiC hybrid material for high-frequency and power electronics

Chen

Bergsten

et al. 2018

Applied Physics Letters

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We demonstrate that 3.5% in-plane lattice mismatch between GaN (0001) epitaxial layers and SiC (0001) substrates can be accommodated without triggering extended defects over large areas using a grain-boundary-free AlN nucleation layer (NL). Defect formation in the initial epitaxial growth phase is thus significantly alleviated, confirmed by various characterization techniques. As a result, a high-quality 0.2-lm thin GaN layer can be grown on the AlN NL and directly serve as a channel layer in power devices, like high electron mobility transistors (HEMTs). The channel electrons exhibit a state-of-the-art mobility of >2000 cm 2 /V-s, in the AlGaN/GaN heterostructures without a conventional thick C-or Fe-doped buffer layer. The highly scaled transistor processed on the heterostructure with a nearly perfect GaN-SiC interface shows excellent DC and microwave performances. A peak RF power density of 5.8 W/mm was obtained at V DSQ ¼ 40 V and a fundamental frequency of 30 GHz. Moreover, an unpassivated 0.2-lm GaN/AlN/SiC stack shows lateral and vertical breakdowns at 1.5 kV. Perfecting the GaN-SiC interface enables a GaN-SiC hybrid material that combines the high-electron-velocity thin GaN with the high-breakdown bulk SiC, which promises further advances in a wide spectrum of high-frequency and power electronics. Published by AIP Publishing.

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confidence: 99%

A GaN–SiC hybrid material for high-frequency and power electronics

Chen

Bergsten

et al. 2018

Applied Physics Letters

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“…Of greater concern is that the defect structure within the GaN layer might be nonhomogeneous due to near-interfacial disorder in the GaN: a high crystalline quality GaN region on top of a low-quality GaN region near the interface. Several transmission electron micrograph studies show that the lowquality GaN region can extend up to the first tens of nanometers from the GaN/AlN interface [5,8,9]. Since the low-quality GaN region is highly localized near the interface with the AlN, its resistance is indistinguishable from the GaN/AlN interface resistance (and thus the effective AlN resistance).…”

Section: Sensitivity Analysismentioning

confidence: 99%

“…These transition films can be highly defective, and this can substantially impair heat conduction from the active GaN regions into the bulk substrate. Electron micrographs of GaN/AlN/SiC composites have shown high densities of dislocations on the order of 10 8 -10 9 cm −2 in the GaN and 10 10 -10 12 cm −2 in the AlN [5][6][7][8]. Reitmeier et al [5] suggested that the initial AlN layers on the growth substrate are nonstoichiometric and thus contain a very high density of point defects, which leads to a high density of dislocations in the near-interfacial volume of the epitaxial layer.…”

Section: Introductionmentioning

confidence: 99%

Phonon scattering in strained transition layers for GaN heteroepitaxy

et al. 2014

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Strained transition layers, which are common for heteroepitaxial growth of functional semiconductors on foreign substrates, include high defect densities that impair heat conduction. Here, we measure the thermal resistances of AlN transition layers for GaN on Si and SiC substrates in the temperature range 300 < T < 550 K using time-domain thermoreflectance. We propose a model for the effective resistance of such transition films, which accounts for the coupled effects of phonon scattering on defects and the two interfaces. The data are consistent with this model using point defects at concentrations near 10 20 cm −3 and transmission coefficients based on the diffuse mismatch model. The data can be also described using lower transmission coefficients and eliminating the defects in the AlN. The data and modeling support the hypothesis that point defect scattering in the AlN film dominates the resistance, but may also be consistent with a high presence of near-interfacial defects in the bounding films.

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“…• C) наблюдаются практически полная релаксация напряжений в самом начале роста [8] и даже переход к растягивающим напряжениям при дальнейшем росте [3]. При росте следующих буферных слоев GaN наблюдается сильная степень релак-сации начальных сжимающих напряжений в ГС GaN/AlN.…”

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Генерация и релаксация напряжений в гетероструктуре (Al, Ga)N/6H-SiC при росте методом плазменно-активированной молекулярно-пучковой эпитаксии

Нечаев¹,

Ситникова²,

Брунков³

et al. 2017

Письма В Журнал Технической Физики

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Исследованы in situ генерация и релаксация напряжений в гетероструктуре Al0.25Ga0.75N/GaN/AlN общей толщиной более 3 mum в процессе ее роста на подложке 6H-SiC методом низкотемпературной плазменно-активированной молекулярно-пучковой эпитаксии при температурах подложки 690-740oC. При комнатной температуре слои AlN и GaN показали остаточные сжимающие напряжения величиной -2.3 и -0.1 GPa соответственно, что позволило исключить растрескивание структуры при ее постростовом остывании. DOI: 10.21883/PJTF.2017.09.44578.16607

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Impact of AlN nucleation layer on strain in GaN grown on 4H-SiC substrates

Cited by 34 publications

References 14 publications

A GaN–SiC hybrid material for high-frequency and power electronics

A GaN–SiC hybrid material for high-frequency and power electronics

Phonon scattering in strained transition layers for GaN heteroepitaxy

Генерация и релаксация напряжений в гетероструктуре (Al, Ga)N/6H-SiC при росте методом плазменно-активированной молекулярно-пучковой эпитаксии

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