METHOD FOR GROWING SINGLE CRYSTALS OF SILICON CARBIDE WITH N-TYPE CONDUCTIVITY Russian patent published in 2022 - IPC C30B23/00 C30B33/02 C30B29/36 

FIELD: crystal growing.

SUBSTANCE: invention relates to the technology of growing silicon carbide single crystals with n-type conductivity by sublimation of silicon carbide powder. The method involves placing a monocrystalline silicon carbide substrate 2 in the crucible 4 parallel to the surface of the polycrystalline silicon carbide powder 3 and heating the silicon carbide powder 3 in an inert gas atmosphere using two coaxially arranged heaters 5, 6, one of which 6 is located on the outside of the crucible 4, and the second 5 – in the central part of the crucible 4, in the placement zone of polycrystalline silicon carbide powder 3, while the upper level X1 of polycrystalline silicon carbide powder 3 is located above the upper end of the heater 5 located in the central part of the crucible 4, the substrate 2 is installed at a distance from the surface of the silicon carbide powder 3, ΔX=X1-X2 =(0.10÷0.20) D, where D is the diameter of the substrate 2, mm, heat treatment of silicon carbide powder 3 is carried out in an inert gas atmosphere at a pressure of 550÷700 mm Hg. and temperature on both heaters 5, 6 of 2200÷2350°C, and then the pressure of the inert gas is reduced to 5.0÷350 mm Hg, the temperature on the external heater 6 to 2050÷2200°C, and the temperature inside the heater 5 to a value of 10÷50°C above that on the external heater 6. The method makes it possible to obtain high-quality silicon carbide crystals with a diameter of more than 100 mm by eliminating polytypic heterogeneity, reducing the density of dislocations, micropores and graphite inclusions. The method also provides for heat treatment of polycrystalline silicon carbide powder evenly throughout the volume in order to homogenize the powder by recrystallizing its dust and fine crystal fractions.

EFFECT: growth mode provides a controlled change in the temperature of the substrate center, as well as conditions for a layered growth mechanism that helps reduce the density of dislocations, micropores and eliminate polytypical heterogeneity.

1 cl, 2 dwg, 3 tbl