Containerless Process for the Spherical Single Crystal Semiconductor Silicon by the Gas Jet Flow Type Electromagnetic Levitation.

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I researched and discussed the fabrication for the spherical single crystal semiconductor Si by using the gas jet flow type electromagnetic levitating process which is one of the containerless process. As with space, this levitating process can solidify metals and semiconductor without convection and container at ground level. Also, this process is new process which enables the high cooling rate and can detects the nucleation from undercooled Si melt. Furthermore, in view of the interaction between Si and high-frequency magnetic field, the sample for electromagnetic levitation is used the surface of high pure(99.999%) Si coated C or B by a high vaccum deposition apparatus. According to the results, this process enabels the containerless solidification for the B or C coated Si. Thereby, the validity of the new electromagnetic levitating process for B or C coated Si is clarified. Also, the undercooling ΔT is 150 K and 200 K for C or B coated Si, respectively. The cooling rate from the cooling start to the detection limit for pyrometer is 110 K/s and 300 K/s for C or B coated Si, respectively. Although crystal growth mode at lower undercoolings of C coated Si samples is faceted growth on the surface, the crystal growth mode of surface Si at higher undercoolings of samples is dendrite grown on the surface. Also, I obtained the a quantitative results about the relation between deposition time and solidification with undercooling of Si sample. From XRD measurements and SEM observation, the Si grain refinement with increasing the undercooling existed and the preferential growth orientation changes with increasing undercooling. As the results, I obtained the high validity of this process and the quantitative data.