Stress-enhanced dislocation density reduction in multicrystalline silicon

• Published in: Physica status solidi. PSS-RRL. Rapid research letters 2011-01, Vol.5 (1), p.28-30
• Main Authors: Bertoni, M. I., Powell, D. M., Vogl, M. L., Castellanos, S., Fecych, A., Buonassisi, T.
• Format: Article
• Language: English
• Subjects: 3-point bending; annealing; Condensed matter: structure, mechanical and thermal properties; Crystal growth; Defects and impurities in crystals; microstructure; Deformation and plasticity (including yield, ductility, and superplasticity); Density; Dislocation density; Dislocations; Exact sciences and technology; high temperature; Linear defects: dislocations, disclinations; Mechanical and acoustical properties of condensed matter; Mechanical properties of solids; Physics; Reduction; Residual stress; Silicon; stress; Stresses; Structure of solids and liquids; crystallography
• ISSN: 1862-6254; 1862-6270; 1862-6270
• DOI: 10.1002/pssr.201004344

Stress is generally perceived to be detrimental for multicrystalline silicon (mc‐Si), leading to dislocation multiplication during crystal growth and processing. Herein, we evaluate the role of stress as a driving force for dislocation density reduction in mc‐Si. At high temperatures, close to the melting point (>0.8Tm), we observe that the application of stress as well as the relief of residual stress, can modify the density of pre‐existing dislocations in as‐grown mc‐Si under certain conditions, leading to a net local reduction of dislocation density. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) This Letter demonstrates that stress plays a role in changing the local pre‐exisiting dislocation density in multicrystalline silicon (mc‐Si) at high temperatures. In samples with pre‐existing dislocations, a high‐temperature annealing in combination with large local stresses is observed to increase the local dislocation density, while small stresses – from applied loads or residual stress – lead to a significant reduction. It is concluded that stress should be viewed as an engineering tool to manipulate the local densities of dislocations in mc‐Si, either during crystal growth or in a re‐annealing step.