Laser tomography of the lifetime and diffusion length of charge carriers in semiconductor silicon ingots

A nondestructive method for estimating quality of single-crystal Si ingots is proposed. The method provides a three-dimensional pattern of the lifetime and diffusion length of charge carriers inside Si ingots up to 300 mm in diameter and 1 m in length. The method employs laser-induced photoinjection of charge carriers followed by laser-assisted monitoring of their spatial distributions and time evolution in any part of the ingot.