Elastic strain in In0.18Ga0.82N layer: A combined x-ray diffraction and Rutherford backscattering/channeling study.

An InGaN layer was grown by metalorganic chemical vapor deposition on a sapphire (0001) substrate using a thick (>2.2 mu m) GaN intermediate layer. The In composition, which cannot be unambiguously determined by x-ray diffraction (XRD) or by photoluminescence, was determined by Rutherford backscattering (RBS). The perpendicular and parallel elastic strain of the In0.18Ga0.82N layer, e(perpendicular to) = + 0.21% and e(parallel to) = -0.53%, respectively, were derived using a combination of XRD and RBS/channeling. The small ratio \e(perpendicular to)/e(parallel to)\ = 0.40 indicates that the In0.18Ga0.82N layer is much stiffer in the c-axis direction than in the a-axis direction. (C) 1999 American Institute of Physics. [S0003-6951(99)01703-9].Physics, AppliedSCI(E)EI37ARTICLE3365-3677

Rutherford backscattering/channeling study of a thin AlGaN layer on Al(2)O(0)3(0001).

A thin AlGaN layer, which is suitable for structural study using Rutherford backscattering (RBS)/channeling, was grown on an Al2O3(0001) substrate by metalorganic chemical vapor deposition. The results show that the composition of the epilayer is Al0.05Ga0.95N and that although the epilayer is very thin (79 nm), it has a good crystalline quality (chi (min) = 1.9%). The azimuthal orientation of the AlGaN epilayer relative to the Al2O3 substrate is AlGaN[0001] // Al2O3[0001] and AlGaN{1120} // Al2O3{1010}, showing that the AlGaN epilayer is rotated by 30 degrees around the [0001] axis with respect to the Al2O3 substrate which decreases the lattice mismatch between the epilayer and the substrate significantly. RES angular scan was used to determine the strain-induced tetragonal distortion of the epilayer. Combined with X-ray diffraction, the perpendicular and parallel elastic strains of the AlGaN layer, e(perpendicular to) = +0.31% and e(parallel to) = -0.28%, can be calculated. (C) 2001 Elsevier Science B.V. All rights reserved.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000167260800022&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Instruments & InstrumentationNuclear Science & TechnologyPhysics, Atomic, Molecular & ChemicalPhysics, NuclearSCI(E)EI8ARTICLE1-2181-18617

Elastic strain in InGaN and AlGaN layers

InGaN and AlGaN layers were grown on Al2O3 substrate by metalorganic chemical vapor deposition (MOCVD) with a GaN intermediate layer. The thickness and the composition of the layers, 270 nm In0.18Ga0.82N and 765 nm Al0.28Ga0.72N, were determined by Rutherford backscattering (RBS). The elastic strain of these layers was determined by X-ray diffraction combined with RBS/channeling. The results show that these layers are partially strained with a perpendicular strain e(perpendicular to) = + 0.21%, parallel strain e(parallel to) = - 0.53% for the InGaN layer and e(perpendicular to) = - 0.16%, e(parallel to) = + 0.39% for the AlGaN layer. The signs of e(parallel to) and e(perpendicular to) of AlGaN are opposite to those of InGaN, since the lattice mismatch between AlGaN and GaN is negative while the lattice mismatch between InGaN and GaN is positive. (C) 2000 Elsevier Science S.A. All rights reserved.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000087378500032&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Materials Science, MultidisciplinaryPhysics, Condensed MatterSCI(E)CPCI-S(ISTP)1