Thermal stress induced dislocation distribution in directional solidification of Si for PV application

• Published in: Journal of crystal growth 2014-12, Vol.408, p.19-24
• Main Authors: Jiptner, Karolin, Gao, Bing, Harada, Hirofumi, Miyamura, Yoshiji, Fukuzawa, Masayuki, Kakimoto, Koichi, Sekiguchi, Takashi
• Format: Article
• Language: English
• Subjects: A1. directional solidification; A1. dislocations; A1. residual strain; A1. thermal stress; Activation; B2. semiconducting silicon; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Crystal growth; Defects and impurities in crystals; microstructure; Dislocation density; Dislocations; Exact sciences and technology; Growth from melts; zone melting and refining; Linear defects: dislocations, disclinations; Materials science; Mathematical models; Methods of crystal growth; physics of crystal growth; Obstacles; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Silicon; Solidification; Structure of solids and liquids; crystallography; Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation; Thermal stresses
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2014.09.017

This paper presents the limitation of the cast technique for silicon growth and the obstacle to reduce the dislocation density below 103cm−2. The thermal stress induced dislocation density, independent of other dislocation sources, is determined and the result suggests that local dislocation densities as high as 104cm−2 are readily introduced alone in the cooling period of the crystal growth. Areas of high residual strain and dislocation densities are identified and presented. The experimental results are correlated with numerical simulation based on a three-dimensional Haasen-Alexander-Sumino (HAS) model. The dislocation introduction is caused by an activation of different slip systems in different ingot areas. •Solely thermal stress induced dislocation density was experimentally determined.•Cooling step of crystal growth introduces up to 104cm−2 dislocations.•Activation of different slip systems causes distinct dislocation pattern.•A good correlation between experiment and simulation could be found.