Ultra High Quality Silicon Carbide Single Crystals Developed by Toyota Central - News Item

Mr. Daisuke Nakamura and colleagues in Toyota Central R&D Labs, Inc. developed ultrahigh-quality silicon carbide single crystals which has fewer dislocation density by two to three orders magnitude than the conventional, and published this research in 26 August 2004 issue of the journal Nature.

Silicon carbide (SiC) has a range of useful physical, mechanical and electronic properties that make it a promising material for next-generation electronic devices. Careful consideration of the thermal conditions in which SiC {0001} is grown has resulted in improvements in crystal diameter and quality: the quantity of macroscopic defects such as hollow core dislocations (micropipes), inclusions, small-angle boundaries and long-range lattice warp has been reduced. But some macroscopic defects (about 1-10 cm^-2) and a large density of elementary dislocations (~10⁴ cm^-2), such as edge, basal plane and screw dislocations, remain within the crystal, and have so far prevented the realisation of high-efficiency, reliable electronic devices in SiC.

Here we report a method, inspired by the dislocation structure of SiC grown perpendicular to the c-axis (a-face growth), to reduce the number of dislocations in SiC single crystals by two to three orders of magnitude, rendering them virtually dislocation-free. Actually, The crystal quality of RAF substrates is much better than that of conventional substrates. We consider that it will be possible in the near future to eliminate dislocations perfectly, and to enlarge the diameter to several inches. These substrates will promote the development of high-power SiC devices and reduce energy losses of the resulting electrical systems.

This result was accomplished with the cooperation of Denso Corporation.

We will present the result at 5th European Conference on Silicon Carbide and Related Materials (ECSCRM2004), Aug. 31- Sept. 4, Bologna, Italy.

Posted August 26^th 2004