Determination of the criterion for the morphological classification of etching pits formed in InSb single crystals grown by the Czochralski method in the crystallographic direction [111] and doped with tellurium

Abstract

The method of selective etching is used to assess the structural imperfection (dislocation density) of single crystals in production conditions due to high informativity and rather low labor consumption. However, the interpretation of the data obtained may differ depending on the choice of the type of regulatory documentation. We present the results of determining the criterion of morphological classification of etch pits using digital image processing. InSb (111) single crystals grown by the Czochralski method and doped with tellurium were analyzed. It was found by the method of sequential selective etching that the island-shaped pits on the surface of InSb (111), are highly likely to be dislocation in nature, regardless of their size. In turn, the clusters of pits of «regular» shape, disappearing in the course of repeated etching, probably arise in the places where point defects come to the surface and are not associated with the formation of Lomer-Cottrell barriers or other dislocation clusters. A criterion for differentiation of etching pits by determining the value of the average pixel intensity is proposed on the basis of brightness field analysis. The results obtained can be used in manufacturing structures for matrix and linear photodetectors, as well as in optimizing process parameters of the single crystal growth by the Czochralski method.