A critical aspect in the development of mono-like Silicon for photovoltaic (PV) application lies in the control of its defect microstructure. While micro-twins do not seem to represent a major concern regarding electrical activity, some dislocations and low angle grain boundaries need to be avoided in the growing process because of their recombination properties. Here, we have studied how these defects grow and interact together in order to understand what are the mechanisms responsible for their presence in the cast ingots. We show that, in our specific convex liquid-solid interface growth mode, micro-twins probably originate from this interface while dislocations and subgrains build up both by epitaxy at the solid liquid interface and through dislocation-boundary interactions in the solidified region. Post-growth TEM characterization allowed identifying constitutive dislocations of some subgrain boundaries for the case of [001] seeds. In-situ TEM straining of Si at high temperature also allowed measuring dislocation mobility at several temperatures. Those are compared to the dislocation velocities in pure Czochralski Si found in literature.

International audienceHigh purity chemically vapor deposited (CVD) diamond single crystals are now widely available. However, the reduction of dislocations in this material still remains an important challenge that will strongly condition its adoption in areas such as optics, electronics, and spintronics, where these defects have a disastrous effect on the properties. In this work we report on a methodology that allows a complete identification of the type, density, and distribution of dislocations in a high quality CVD single crystal. A good agreement between all characterization techniques was established. When the surface is adequately prepared, a simple plasma etching allows evidencing 2 main dislocation types: 45° mixed and edge, with the latter one being dominant with a density of around 4.5 × 104 cm–2. This investigation paves the way to the development of a quick and simple process to analyze dislocations toward getting a better understanding of their impact on the material properties and eventually elaborating strategies to eliminate them