Elastic strains in heteroepitaxial ZnSe1-xTex on InGaAs/InP (001)

Here we report on the elastic strains in ZnSe1-xTex (x < 0.9) epitaxial layers grown using photo-assisted metalorganic vapor phase epitaxy on In0.53Ga0.47As/InP (001) substrates. High-resolution x-ray diffraction was used to determine their composition and strain. At room temperature, we observed an apparent asymmetry in strains for tensile and compressive layers. However, when we accounted for the difference in thermal expansion between the substrate and epitaxial material, the growth temperature strain relaxation appears symmetric with respect to the sign of mismatch. The growth temperature strains are in agreement with the Matthews and Blakeslee (MB) model [J.W. Matthews and A.E. Blakeslee, J. Cryst. Growth 27, 118 (1974)] for both compressive (x > 0.6) and tensile (x < 0.4) layers. However, for the layers with composition in the range 0.4 < x < 0.6, the growth temperature strains exceed the values predicted by the MB theory. Apparently, low-mismatch layers experience a kinetic barrier to relaxation. The overall behavior can be fit by the relaxation model of Dodson and Tsao [B.W. Dodson and J.Y. Tsao, Appl. Phys. Lett. 51, 1325 (1987)] using the values Cmu=80 s and gamma0=10.