Mono-crystalline growth in directional solidification of silicon with different orientation and splitting of seed crystals

This work presents the results of a systematic study of mono- and poly-crystalline grain growth in directional solidification of silicon using different kinds of seed crystals. The seed orientation was varied between 〈100〉, 〈111〉 and 〈110〉. In some experiments the seeds were split into several seed pieces. The results show that the growth of misoriented grains at the crystal periphery as well as in the gaps between split seeds depends strongly on the crystallographic orientation of the seeds. It is shown that this problem can be minimized if certain seed orientations and combinations are chosen. Generally the 〈100〉 seed orientation turns out to be most difficult with respect to mono-crystalline growth. Heterogeneous nucleation originating from the crucible walls seems to be a minor problem.

► Growth of different oriented mono-crystals by casting technique is possible.
► Detailed investigation of the mc-grain structure in the crystals periphery.
► Proposal of a growth model which includes a twinning process.
► Validation of the model by experimental data.