Direct Observation of Dislocations in a LEC-GaP Crystal by Light Scattering Method

Abstract

The 90°-angle light scattering method (ultramicroscopy) has been used to investigate the crystalline quality of a liquid encapsulated Czochralski (LEC) GaP crystal. Observed scattering patterns have been attributed to grown-in dislocations. It is believed that the patterns are caused by minute scattering centers, probably impurity precipitates along the dislocations. This observation method has the advantages of obtaining the clear mapping of the dislocations nondestructively and using no decoration technique. A comparison of the scattering patterns between LEC-GaP and synthesis-solute-diffusion (SSD) GaP (growth temperature: 1050°C) is made, and SSD-GaP is found to be scattering center free. This result suggests that the scattering centers are related to the higher temperature growth of the LEC-GaP (1470°C).