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

Abstract

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...

Strain contrast of GaNyAs1−y(y= 0.029 and 0.045) epitaxial layers on (100) GaAs substrates in annular dark field images

“…The lattice constants of GaAs and GaN y As 1−y are 0.565 33 nm and 0.565 33-0.114 99y nm respectively [13]. The whole GaN y As 1−y film is under biaxial tensile strain and the strain is accommodated by the tetragonal distortion of the GaN y As 1−y lattice [13]. Considering a coordinate system in which the y axis is parallel to the (100) growth direction and the plane containing the x and z axes is parallel to the film-substrate interface plane, after the epitaxial growth, the lattice constants of GaAs remain at the bulk values of a = b = c = 0.565 33 nm.…”

“…Since the GaAs substrates are much thicker than the DQW layers, all of the strain can be assumed to be confined in the DQW layers and there is no strain in the GaAs substrates. The lattice constants of GaAs and GaN y As 1−y are 0.565 33 nm and 0.565 33-0.114 99y nm respectively [13]. The whole GaN y As 1−y film is under biaxial tensile strain and the strain is accommodated by the tetragonal distortion of the GaN y As 1−y lattice [13].…”

“…including the control and determination of the N concentration and optical properties of the DQW laser have been reported previously [3,4,12]. All five layers in each active region are fully strained and free of defects [12,13]. 011 cross-sectional TEM samples were prepared following standard dimpling and ion milling procedures.…”

Effects of small specimen tilt and probe convergence angle on ADF-STEM image contrast of Si0.8Ge0.2 epitaxial strained layers on (100) Si

“…Conventional transmission electron microscopy (CTEM) has played an important role in characterizing strained epitaxial films. For example, CTEM studies of defects (dislocations, twins, stacking faults and cracks) and morphology helped to determine the strain relaxation mechanisms in SiGe/Si, InGaAsP/InP, GaAsN/GaAS films, which then facilitated optimization of growth methodology [2][3][4][5]. In recent years, annular dark field scanning transmission electron microscopy (ADF-STEM) has become a widely used and powerful technique for characterizing strained epitaxial layers due to the fact that ADF-STEM image contrast depends strongly on the atomic number Z of the scattering atoms in a simple Z n form (n¼1.6-1.9), which makes composition variation evident through a change in image intensity [6][7][8][9][10].…”

Atomic Size Mismatch Strain Induced Reversed ADF-STEM Image Contrast Between dilute Semiconductor Heteroepitaxial Layers and Substrates

“…The incorporation of small amounts of nitrogen (N) into GaAs leads to a large decrease in the bandgap energy and has enabled the growth of GaAs-based laser diodes functioning in the 1.3-1.55 µm wavelength range [1]. Conventional transmission electron microscopy (TEM) has played an important role in characterizing the layer morphology and defects in heteroepitaxial strained films, which helps to optimize the growth methodology and elucidate the strain relaxation mechanisms [3,4]. However, one cannot easily distinguish between atomic species in heterostructures from the contrast in conventional high resolution TEM images.…”