QUANTITATIVE CHARACTERIZATION OF RESIDUAL STRAINS IN GALLIUM-PHOSPHIDE (100) WAFERS

Residual strains in thin GaP (100) wafers, sliced from crystalline ingot grown by the liquid-encapsulated Czochralski method, have been first characterized by measuring strain-induced birefringence. The absolute values of the residual strain components \S(r)-S(t)\, \S(yy)-S(zz)\, and 2\S(yz)\ are quantitatively characterized. It is found that their two-dimensional distribution maps exhibit fourfold symmetry and that most of wafers exhibit U- or M-shape distributions along diametric directions, but some wafers with a low level of strains exhibit distorted-shape distributions. The maximum strain value attains to the order of 10(-4) and the corresponding stress is about 7.5 X 10(6) N/m2.