Influence of Crystalline Orientation on Photoelastic Property of Si Single Crystal.

Abstract

We developed an optical birefringence measurement method that uses a photoelastic modulator and a polarized laser. A He-Ne infrared laser was adopted as the light source for measuring the optical birefringence in gallium arsenide wafers. In this paper we explain the theory and the process of measurement of stress in GaAs wafers. The magnitude of principal stress difference and also the directions of the principal stresses were obtained simultaneously and quantitatively using our developed equipment. The optical birefringences of {100} GaAs stressed specimens were measured. From the experimental results, it was found that the photoelastic constant depended on the crystalline orientation and that the birefringence direction did not coincide with the principal stress direction. By stress-strain analysis of the GaAs single crystal, it was found that the birefringence direction coincided with the principal strain direction and that the relationship between the principal strain difference and the birefringence was independent of crystalline orientation.