Residual strain as a measure of wafer quality in indium phosphide crystals

The quantitative photoelastic technique was utilized to characterize residual strain as a measure of InP wafer quality. A series of standard wafers (Sn-doped, 2-inches, LEC-grown InP) received commercially from four different wafer suppliers were characterized and compared to demonstrate the feasibility of residual strain as the quality measure. In order to understand the residual strain well, the generation mechanism was modeled and explained in conjunction with plastic deformation originating dislocation generation due to thermal stress caused during various processes in crystal growth and device fabrication.