The Precipitation of Nickel and Copper at Grain Boundaries in Silicon

Abstract

The precipitation of copper and nickel at grain boundaries in cast polycrystalline silicon is investigated. The metals are diffused into the specimens from a surface source between 800 – 1000 °C and the precipitation after cooling is studied by TEM. Copper precipitates in form of colonies containing hundreds of particles with a size between 5–6 nm. In the grain boundary they nucleate preferentially at dislocations and steps. The distribution and size of the precipitates depend on the cooling rate after the diffusion. Nickel forms only few large (micrometer size) plate-like or three dimensional precipitates at and near grain boundaries. The main features of the results and the differences between the two elements are explained under the assumption that the precipitation requires the transport of native point defects.

Scanning infrared microscopy investigation of copper precipitation in cast multicrystalline silicon

“…But up to now, few papers have been published about copper precipitation in cast multicrystalline silicon (mc-Si) [19,20]. Moeller et al [19] observed with TEM the micro-feature of copper precipitates in mc-Si and found that copper nucleated preferentially at dislocations and at steps of grain boundaries. McHugo et al [20] mainly studied the gettering effect of copper in mc-Si.…”