X-Ray Scattering from Semiconductors

Fewster, Paul F.

doi:10.1142/p137

Cited by 117 publications

(85 citation statements)

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“…The advantage of this approach is that the substrate distortions and uncertainties are irrelevant. 15 In this letter, we studied the anisotropic crystallographic characteristics of m-plane GaN films grown on LiAlO 2 ͓LAO͔͑100͒ substrates. Williamson-Hall ͑W-H͒ plots reveal different tilts and lateral correlation lengths along the two orthogonal directions.…”

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confidence: 99%

“…The interplanar spacing normal to the interface can be obtained from symmetric reflection; that in the plane of the interface can be obtained by comparing the positions of two reflections. 15 To the situation of m-plane GaN, it should define the interplanar spacings in GaN layer as an orthogonal set d z and d x in the plane of the interface and d y normal to the interface plane. These parameters can be calculated from the symmetric and asymmetric RSMs of several reflections.…”

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confidence: 99%

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Anisotropic crystallographic properties, strain, and their effects on band structure of m-plane GaN on LiAlO2(100)

Liu

Zhang

Xie

et al. 2008

Applied Physics Letters

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The m-plane GaN films grown on LiAlO 2 ͑100͒ by metal-organic chemical vapor deposition exhibit anisotropic crystallographic properties. The Williamson-Hall plots point out they are due to the different tilts and lateral correlation lengths of mosaic blocks parallel and perpendicular to GaN͓0001͔ in the growth plane. The symmetric and asymmetric reciprocal space maps reveal the strain of m-plane GaN to be biaxial in-plane compress xx = −0.79% and zz = −0.14% with an out-of-plane dilatation yy = 0.38%. This anisotropic strain further separates the energy levels of top valence band at ⌫ point. The energy splitting as 37 meV as well as in-plane polarization anisotropy for transitions are found by the polarized photoluminescence spectra at room temperature. © 2008 American Institute of Physics. ͓DOI: 10.1063/1.2951618͔The wurtzite structure of III-nitrides leads to electrostatic fields along the ͓0001͔ direction due to spontaneous and piezoelectric polarization, when the film is grown on c-oriented substrates. 1 These built-in electric fields along the ͓0001͔ direction separate the electron and hole wave functions in a quantum well ͑QW͒ thereby reducing the recombination probability of electron-hole pairs. Consequently, it results in reduction of quantum efficiency of light-emitting diodes. 2 A way to overcome this deficiency is to grow GaNbased QWs along nonpolar orientations, for example, m plane 3,4 or a plane. 5,6 It has been shown that the electric field can be avoided in such nitride QWs. When ͓1100͔ or ͓1120͔ becomes the growth direction, the c axis of GaN lattice lies down in the growth plane. As a consequence, the C 6v hexagonal symmetry of the c growth plane is reduced to C 2v symmetry of the m growth plane. Firstly, it would show the anisotropic crystallographic characteristics. 7,8 Secondly, the nonpolar GaN films experience strong anisotropic deformation due to different in-plane lattice mismatches and thermalexpansion coefficients between GaN and underlying substrates. In the case of c-plane GaN films, isotropic strain in the c-plane preserves C 6v symmetry in the x-y plane so that no significant in-plane physical anisotropy occurs. The situation is quite different for nonpolar GaN films. Anisotropic in-plane strain components further lift the symmetry in the growth plane, which significantly modify the top three valence band ͑VB͒ states at ⌫ point. 9,10 Both the energy splitting and polarization selection of the transitions between conduction band ͑CB͒ and VB have been observed by absorption, reflectance, and photoreflectance spectroscopy. 11,12 Recently, transmission anisotropy spectroscopy has been utilized to obtain the energy splitting and polarization information of m-plane GaN films. 13 Although the in-plane strain components are important for the modifications in band structure of nonpolar GaN, it is still difficult to experimentally determine the full state of strain. In the case of m plane, GaN films are grown along GaN ͓1100͔ direction. The growth plane is the x-z plane, and the growth direc...

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Anisotropic crystallographic properties, strain, and their effects on band structure of m-plane GaN on LiAlO2(100)

Liu

Zhang

Xie

et al. 2008

Applied Physics Letters

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“…15 Figure 2͑b͒ shows the bending of the FS films as a function of the difference in the in-plane lattice parameters of the Ga and N face sides for all the samples. A clear reduction of the bending in the annealed samples can be seen although it remains significant in all the FS films.…”

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confidence: 99%

Effect of high-temperature annealing on the residual strain and bending of freestanding GaN films grown by hydride vapor phase epitaxy

Paskova

Hommel

Paskov

et al. 2006

Applied Physics Letters

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The effect of high-temperature high-pressure annealing on the residual strain, bending, and point defect redistribution of freestanding hydride vapor phase epitaxial GaN films was studied. The bending was found to be determined by the difference in the in-plane lattice parameters in the two faces of the films. The results showed a tendency of equalizing the lattice parameters in the two faces with increasing annealing temperature, leading to uniform strain distribution across the film thickness. A nonmonotonic behavior of structural parameters with increasing annealing temperature was revealed and related to the change in the point defect content under the high-temperature treatment.

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“…The correlation length and tilt are related to the parallel and radial component of the elliptically-shaped Bragg peak (see inset, Fig. 1a) [13]. For this particular film, the long-axis of the ellipse is essentially normal to the radial direction, which indicates a long lateral correlation length.…”

Section: Methodsmentioning

confidence: 88%

Strain relaxation in GaNyAs1−y films on (100) GaAs

Baribeau

Gupta

et al. 2005

Journal of Crystal Growth

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Access and use of this website and the material on it are subject to the Terms and Conditions set forth at Strain relaxation in InNyAs1-y films on (100) GaAs Wu, X.; Baribeau, J. -M.; Gupta, J. A.; Beaulieu, M.http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=fr L'accès à ce site Web et l'utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D'UTILISER CE SITE WEB. NRC Publications Record / Notice d'Archives des publications de CNRC:http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?action=rtdoc&an=12744125&lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?action=rtdoc&an=12744125&lang=fr READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE.http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. Questions? Contact the NRC Publications Archive team atPublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information. NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://doi.org/10.1016/j.jcrysgro.2005.04.081 Growth, 282, 1-2, pp. 18-28, 2005-08-15 Journal of Crystal Growth 282 (2005) Journal of Crystal AbstractThe strain relaxation behavior for a series of GaN y As 1Ày films was studied by transmission electron microscopy, high-resolution X-ray diffraction and atomic force microscopy. Samples consisting of 200 nm thick GaN y As 1Ày epitaxial layers with 0:025pyp0:065 (i.e. various misfit strain) were grown on (1 0 0) GaAs substrates by molecular beam epitaxy at 460 1C. The GaN 0.025 As 0.975 film shows no misfit dislocations and remains pseudomorphic well beyond the Matthews and Blakeslee's critical thickness, which can be explained by the high activation energy for a homogeneous dislocation nucleation at a smooth film surface. In samples with large N content (y40:04) relaxation of the built-in strain proceeds through morphological changes involving formation of surface cusps, followed by stacking faults and microtwins. The surface nucleation of 901 partial dislocations is shown to be feasible at the low growth temperature in the presence of cusps due to the stress concentration. The surface roughness is anisotropic between the two /011S direc...

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X-Ray Scattering from Semiconductors

Cited by 117 publications

References 1 publication

Anisotropic crystallographic properties, strain, and their effects on band structure of m-plane GaN on LiAlO2(100)

Anisotropic crystallographic properties, strain, and their effects on band structure of m-plane GaN on LiAlO2(100)

Effect of high-temperature annealing on the residual strain and bending of freestanding GaN films grown by hydride vapor phase epitaxy

Strain relaxation in GaNyAs1−y films on (100) GaAs

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