High-speed growth of Si single bulk crystals by expanding low-temperature region in Si melt using noncontact crucible method

Abstract

We propose a high speed growth based on noncontact crucible method for obtaining large ingots with a constant diameter. In this method, the Si melt used has a large low-temperature region in its central upper part to ensure Si crystal growth inside it. Therefore, this method has the possibility of attaining a high growth rate using a high cooling rate because the growth rate is determined by the rate of expansion of the low-temperature region in the Si melt. The horizontal and vertical growth rates in Si melts were experimentally determined. At a cooling rate of 0.4 K/min, the horizontal growth rate reached 1.5 mm/min in the <110> direction and 1.9 mm/min in the <100> direction. These growth rates are higher than that of the cast method. The growth rate increased with the cooling rate. The vertical growth rate was determined to be 0.3 0.6 mm/min, and it tended to increase with increasing depth of the Si melt. The diameter of an ingot remained constant during pulling due to a high cooling rate of 0.4 K/min because the horizontal growth rate increased as the cooling rate increased and the melt temperature markedly decreased. An ingot with a constant diameter of 21 cm and a height of 7 cm was obtained inside a Si melt by the high speed growth using a crucible with 33 cm diameter.

Comparison between laser terahertz emission microscope and conventional methods for analysis of polycrystalline silicon solar cell

“…THz waves are generated by the transient current modulation. Electromagnetic waves in the THz range based on classical electromagnetic theory are approximately expressed by equation (1). The electric field E(t) is proportional to the time derivative of J(t) as expressed in the following equation 20 :…”

“…The THz emission at point 2 has higher intensity than that at points 1, 3, and 4. THz waves are generated from the photoexcited carriers accelerated by the local electric field as expressed by equation (1). The electric potential is affected by imperfections in crystals such as defects and dislocations.…”

“…[1][2][3] A recent study on PbS quantum dots for next-generation solar cells revealed that the electron and hole should be separated within a lifetime of a few tens of picoseconds for realizing a multiple exciton generation (MEG) solar cell. 4 It is therefore important to investigate the dynamic response of photoexcited carriers in solar cells in the picosecond range.…”

Growth of Si Bulk Crystals with Large Diameter Ratio Using Small Crucibles by Creating a Large Low-Temperature Region Inside a Si Melt Contained in an NOC Furnace Developed Using Two Zone Heaters

“…[1][2][3][4][5][6][7][8] This method is similar to the Kyropoulos method. [9][10][11] In the NOC method, however, a low-temperature region must be intentionally established in a Si melt.…”

“…The shape of the growing interface is generally convex in the growth direction. The growth rate is determined by the rate of expansion of the low-temperature region in the Si melt, 6 and the expansion rate of the low-temperature region is mainly determined by the cooling rate of the Si melt. 6 Therefore, a high growth rate can be attained using a high cooling rate even though crystals grow inside the crucible, similarly to the cast method.…”