3D visualization of growth interfaces in cast Si ingot using inclusions distribution

Abstract

• A method of 3D visualization of growth interface in cast silicon ingots is proposed. • The method utilizes inclusion distribution along with the growth interface. • Inclusion distribution is measured by an infrared brick inspection system. • The interface is extracted by fitting with a simple polynomial expression. • This visualization will contribute to the development of the crystal growth method. We propose a method of three-dimensional (3D) visualization of growth interfaces in crystalline ingots prepared by directional solidification and apply the method to cast silicon ingot for solar cells. The method consists of dispersing inclusions along with the growth interface by insertion of a quartz rod followed by measuring inclusions distribution by an infrared brick inspection system. Then, inclusions distribution can be visualized in 3D, which allows extracting growth interfaces as planes. By fitting the plane with a simple polynomial expression, its macroscopic shape and local gradient can be estimated. The method yields us the local changes in growth interfaces and thus contributes to the development of the crystal growth method for high-quality ingots.