Effect of AlN interlayers in the structure of GaN-on-Si grown by plasma-assisted MBE

Adikimenakis, A.; Sahonta, S.‐L.; Dimitrakopulos, G. P.; Domagała, J. Z.; Kehagias, Th.; Komninou, Ph.; Iliopoulos, E.; Georgakilas, A.

doi:10.1016/j.jcrysgro.2008.10.085

Cited by 10 publications

(6 citation statements)

References 26 publications

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“…The AlN layers are too thin for the cracks to be resolved in the cross-sectional images. Observation of micro-cracks in thin AlN ILs has been also been reported in literature [2,8]. Fig.…”

Section: Methodssupporting

confidence: 68%

Role of buried cracks in mitigating strain in crack free GaN grown on Si (111) employing AlN interlayer schemes

Tang¹,

Baribeau²,

Aers³

et al. 2011

Journal of Crystal Growth

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This paper investigates the effect of buried cracks in the AlN interlayer buffer on mitigation of the large, tensile, thermal expansion mismatch strain in the GaN/Si system, which is a key hurdle for achieving crack free GaN epitaxy on silicon. The thermally induced strain is determined by temperature-dependent, highresolution X-ray diffraction measurements carried out from room temperature up to the growth temperature. It is found that in addition to the balancing effect of compressive lattice-mismatch strain induced by the AlN interlayers, buried cracks in the AlN interlayer region can also relax some of the thermal expansion mismatch strain through elastic distortion at crack edges. The degree of relaxation is dependent on the spacing-to-height aspect ratio of the buried cracks, consistent with prediction of crackedge-induced relaxation models.Crown

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“…The AlN layers are too thin for the cracks to be resolved in the cross-sectional images. Observation of micro-cracks in thin AlN ILs has been also been reported in literature [2,8]. Fig.…”

Section: Methodssupporting

confidence: 68%

Role of buried cracks in mitigating strain in crack free GaN grown on Si (111) employing AlN interlayer schemes

Tang¹,

Baribeau²,

Aers³

et al. 2011

Journal of Crystal Growth

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“…As has been presented in detail elsewhere [16], the promotion of a rough growth front, particularly after the introduction of a large density of threading dislocations, leads to extensive IDB formation. This is due to the exposure of pyramidal crystallographic facets, primarily {1011} planes bounding V-shaped defects, which are often the terminations of threading dislocations at the growth surface.…”

Section: Thick Aln Ilsmentioning

confidence: 71%

“…However, the optimum IL thickness is still unclear, as well as the manner in which it is influenced by the growth conditions and the operating strain relaxation mechanisms. In a recent contribution, Adikimenakis et al [16] have suggested the IL thickness of 15 nm for nitrogen radio frequency plasma source molecular beam epitaxy (RFMBE). RFMBE offers lower growth temperatures, which reduce the thermally induced tensile stress.…”

Section: Introductionmentioning

confidence: 99%

Strain accommodation and interfacial structure of AlN interlayers in GaN

Dimitrakopulos

Kalesaki

Komninou³

et al. 2009

Cryst. Res. Technol.

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The strain accommodation mechanisms at AlN interlayers in GaN, grown by radio‐frequency plasma assisted molecular beam epitaxy, are studied using transmission electron microscopy techniques and atomistic modelling. Interlayers of various thicknesses grown within GaN epilayers deposited on both sapphire and silicon substrates have been employed. Interlayers of thickness below 6 nm do not exhibit line defects although local roughness of the upper interlayer interface is observed as a result of the Al adatom kinetics and higher interfacial energy compared to the lower interface. Above 6 nm, introduction of a‐type misfit and threading dislocations constitutes the principal relaxation mechanism. Due to strain partitioning between AlN and GaN, threading dislocations adopt inclined zig‐zag lines thus contributing to the relief of alternating compressive‐tensile elastic strain across the AlN/GaN heterostructure. The observed dislocation configurations are consistent with a model of independent motion by climb or ancillary glide in response to their localized three‐dimensional strain environment. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…Moreover, the difference in the thermal expansion coefficients between Si and GaN leads to thermally induced tensile stress, which is partially relaxed by the formation of microcracks in the films. Microcracks can be avoided utilising one or more intermediate AlN layers [1,2,3] in order to introduce compressive residual strain in the overgrown GaN layers, due to the lattice mismatch between GaN and AlN. The remaining tensile stress is then reduced below the threshold value for microcrack formation.…”

mentioning

confidence: 99%

Mechanism of Si outdiffusion in plasma‐assisted molecular beam epitaxy of GaN on Si

Adikimenakis

Aretouli

Tsagaraki

et al. 2012

Phys. Status Solidi C

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The mechanism of Si outdiffusion related to the formation of Si‐rich GaN clusters during the growth of GaN‐on‐Si by plasma‐assisted molecular beam epitaxy (PAMBE) has been identified. GaN thin films were grown, on high resistivity Si (111) substrates at Ga‐rich conditions to favour the 2D step‐flow growth mode. Hall‐effect measurements revealed very high electron background concentrations, ranging from 2 x 1018 cm‐3 to 3 x 1019 cm‐3, with degraded carrier mobility in the range of 5‐30 cm2/Vs. SEM examination of surfaces and cross‐sections of the samples revealed the presence of hollow GaN clusters on the film surface and voids at the Si/III‐nitride interface. EDX spot analysis revealed dissolution of Si material in the GaN clusters. Growth of GaN on Si under stoichiometric conditions resulted in films without GaN clusters, which exhibited a serious reduction in carrier concentration, down to 1.4 x 1016 cm‐3, with a simultaneous increase of the carrier mobility to 137 cm2/Vs. C‐V carrier profile measurements were consistent with Hall‐effect measurements and revealed a uniform electron concentration in the GaN film, down to the AlN nucleation layer (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Effect of AlN interlayers in the structure of GaN-on-Si grown by plasma-assisted MBE

Cited by 10 publications

References 26 publications

Role of buried cracks in mitigating strain in crack free GaN grown on Si (111) employing AlN interlayer schemes

Role of buried cracks in mitigating strain in crack free GaN grown on Si (111) employing AlN interlayer schemes

Strain accommodation and interfacial structure of AlN interlayers in GaN

Mechanism of Si outdiffusion in plasma‐assisted molecular beam epitaxy of GaN on Si

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