Elastic contants and Poisson ratio in the system AlAs-GaAs

Near infrared Brillouin scattering was used to determine all three elastic constants, and hence Poisson's ratio v=C12/(C11 plus C12) of epitaxial Al(ind x)Ga(ind 1-x)As layer on GaAs. The Al(ind x)Ga(ind1-x)As layers were grown by metalorganic chemical vapor deposition and molecular beam epitaxy. We found evidence for a slight bowing in all elastic contants versus Al composition x. The elastic constants of AlAs were determined to be C11=119.9 GPa+/-1.2 GPa, C12=57.5 GPa+/-1.3 GPa, and C44=56.6 GPa+/-0.7 GPa. From x-ray measurements and the Poison trio v=0.324+/-0.004 the relaxed (cubic) AlAs lattice constant is found to be a(ind AlAs)=5.661 72 Angstrom Unit+/-0.000 08 Anstrom Unit.