Characterization of InGaN/GaN heterostructures by means of RBS/channeling

InxGa1-xN epitaxial layers with 0 < x < 0.12 were grown on GaN/sapphire substrates by the MOCVD technique. These layers were characterized by means of the RBS/channeling technique. The following layer parameters were determined: composition x, lattice distortion due to In incorporation and strain values. The linear dependence between the energy of photoluminescence on the In content has been established. The perpendicular strain epsilon(perpendicular to) = 0.77%, and parallel strain epsilon(parallel to) = -0.45% were determined. These parameters indicate that the epilayer is under tensile stress in the perpendicular direction and under the compressive stress in the parallel one. The ratio \epsilon(perpendicular to)/epsilon(parallel to)\ = 1.71 is quite close to 2 which is characteristic for strained layers if the volume is conserved. The increase of the In minimum yield with increasing x indicates phase segregation in the epilayer. (C) 2000 Elsevier Science B.V. All rights reserved.