Quantitative photoelastic measurement of residual strains in undoped semi-insulating gallium arsenide

Abstract

A new quantitative photoelastic method has been developed to measure residual strains in undoped semi-insulating (001) GaAs substrates for integrated circuits. The absolute values of the shear strain ∥exy∥ and the difference of the expansion and contraction strains ∥e yy-exx∥ existing in the (001) substrate plane are quantitatively determined by using the present method. Their two-dimensional distribution maps are demonstrated to exhibit fourfold symmetries rotating 45°to each other. The absolute values are found to be of the order of 10-5 at the substrate edges.