Quantitative photoelastic characterization of residual strain and its correlation with dislocation density profile in semi-insulating LEC-grown GaAs wafers

By using a newly-developed computer-controlled infrared polariscope, strain-induced birefringence has been measured to characterize residual strain in thin LEC-grown GaAs [100] wafers. It is found that the residual strain profile exhibit fourfold symmetry and the maximum value attains to the order of 10/sup -5/ /spl sim/ 10/sup -4/. EPD profile has been also measured to explore a correlation between the residual strain and EPD. A model is proposed to explain the correlation between the residual strain and EPD profiles, which is found fairly to explain the present experimental results.