Simulation Studies of Annealing Effect on a mc-Si Ingot for Photovoltaic Application

Abstract

A multi-crystalline silicon (mc-Si) ingot was grown by the directional solidification (DS) process for photovoltaic (PV) application. We have numerically investigated shear stress and thermal stress for different annealing time and temperature of the directionally solidified mc-Si ingot after the solidification and also we discuss the melt-crystal (m-c) interface during the solidification. Initially the planar m-c interface is observed during the solidification process, after that a slightly convex m-c interface is obtained for the rest of the solidification process. Maximum shear stress has least value at the center region of the mc-Si ingot for 900 K annealing temperature. Maximum shear stress has least value at the peripheral region of the mc-Si ingot for 700 K annealing temperature. The whole mc-Si ingot has lower thermal stress at 700 K annealing temperature. 5 h annealing time is enough to decrease the internal stress of the mc-Si ingot. Increase of the annealing time beyond 5 h does not further decrease the stress significantly.