Relationship between lattice parameters and compositions of molecular beam epitaxial Hg 1－x Cd x Te films

High_resolution x_ray diffraction technology is applied to the measurement of la ttice parameters and the study of strain for Hg 1-x Cd x Te fi lms gr own by molecular beam epitaxy. The results show that there exist both perpendicu lar strain and shear strain in Hg 1-x Cd x Te films. Based on crystal elastic theory, strain states in Hg 1-x Cd x Te films are analyz ed and calculated, and the lattice parameters of 1-x Cd x Te film s at the relaxation state are obtained. It is found that the relationship betwee n lattice parameters and compositions of Hg 1-x Cd x Te films agrees with Vegard's law, rather than Higgins formula proposed in earlier research. It is also found that the lattice parameters can be derived from the measured data of (224) plane spacing, and that the compositions of Hg 1-x Cd x Te films can also be evaluated by using Vegard's law with an error about 0 01.