Interactions of twin boundaries and dislocations in solar silicon. Topical technical report, October 1, 1983-June 28, 1984

Technical Report · Fri Jun 01 04:00:00 EDT 1984

DOI:https://doi.org/10.2172/6898116· OSTI ID:6898116

Gleichmann, R.; Ast, D. G.

Most solar materials grown under the JPL program contain twin boundaries (e.g. EFG and WEB). These twin boundaries interact with dislocations during: (i) Plastic deformation during cool-down; (ii) stress relaxation during formation of the diffused junction. In (i) the twin boundaries restrict the movement of dislocations resulting in higher residual stresses being frozen in into the ribbon. In (ii) the twin boundaries act as concentrators of dislocations which lead to the formation of sub-boundaries, which, penetrating a junction, lead to junction defects. For these reasons it is important to understand the mechanism of interaction. TEM and EBIC were used to study changes in the defect structure which occurred when rapidly grown, edge defined film fed growth silicon ribbons were processed at high temperatures. Twin boundaries, which comprise the major structural defects in the ribbons were found to act as strong obstacles to dislocation glide. The impedance of dislocation glide, possible mechanisms for slip transfer across twins, and implications for the mechanical and electrical properties of the silicon ribbons are discussed. A model is developed which explains both twin-induced grain boundary formation during recovery of the microstructure and also the generation of microtwins and second order twin joins by glide-induced twinning processes.

• Research Organization: Cornell Univ., Ithaca, NY (USA). Dept. of Materials Science and Engineering
• DOE Contract Number: NAS-7-100-956046
• OSTI ID: 6898116
• Report Number(s): DOE/JPL/956046-10; ON: DE84013135
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140501* -- Solar Energy Conversion-- Photovoltaic Conversion
36 MATERIALS SCIENCE
360602 -- Other Materials-- Structure & Phase Studies
CRYSTAL DEFECTS
CRYSTAL GROWTH METHODS
CRYSTAL STRUCTURE
DISLOCATIONS
EFG METHOD
ELECTRON MICROSCOPY
ELEMENTS
GRAIN BOUNDARIES
LINE DEFECTS
MICROSCOPY
MICROSTRUCTURE
SEMIMETALS
SILICON
TRANSMISSION ELECTRON MICROSCOPY
TWINNING