DETERMINATION OF THE COMPOSITION OF STRAINED TETRAGONAL EPILAYERS

Elasticity theory is applied to calculate the total strain present in a tetragonal symmetry epilayer due to heteroepitaxial misfit. By relat ing pseudobinary alloy composition to the lattice constants of the epi layer, it is shown that the composition of a pseudobinary epilayer can be determined from measurement of the strained epilayer lattice const ants. This is accomplished by expressing the misfit strain in terms of the composition and the individual lattice constants of the component s of the epilayer and using Vegard's rule. As a result, determination of the composition of two chalcopyrite symmetry epilayers from x-ray d iffraction measurements is demonstrated. The approach presented here i s general and can be applied to any substrate-epilayer combination in the elastic limit. (C) 1996 American Institute of Physics.