MECHANICAL MICROSTRESSES IN DISLOCATION-FREE FLOATING-ZONE SILICON MONOCRYSTALS

Silicon monocrystals belong to the cubic system (class m3m), which means that they are inherently optically isotropic, i. e. they do not exhibit rotation of the polarization plane of light in any crystallographic direction. The photoelasticity technique, involving the application of a He-Ne laser ( lambda equals 1. 15 mu m), was used to examine the residual mechanical microstresses in dislocation- and swirl-free floating zone monocrystals. The reasons causing stresses are analysed and methods to eliminate them are elaborated.