N-type SiC Crystal Growth via Nitride Doping in Si-C Solution
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Solution Overview
Problem
Existing methods for growing n-type SiC single crystals, such as those involving nitrogen gas supply, face challenges with increased growth rate leading to the generation of miscellaneous crystals, hindering the production of high-quality single crystals with low resistivity.
Innovation Solution
A method involving a SiC seed crystal substrate contacted with a Si-C solution having a temperature gradient, where a nitride is added to the starting material or solution to maintain a uniform nitrogen concentration, facilitating rapid growth of n-type SiC single crystals with low resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If nitrogen gas is supplied into a crucible to grow an n-type SiC single crystal by solution process, then the resistivity of the grown crystal is reduced, but increasing the growth rate leads to generation of miscellaneous crystals
Solution Approach 1:
The patent changes the nitrogen supply method from gas phase to solid phase (nitride powder), and adjusts the concentration of nitrogen in the Si-C solution to an optimal range (0.01-5 mass%). This parameter optimization allows achieving both low resistivity (high crystal quality) and high growth rate without generating miscellaneous crystals, thereby resolving the technical contradiction between manufacturing precision and productivity
Solution Approach 2:
The patent introduces a nitride powder as an intermediary substance that mediates between the Si-C solution and nitrogen supply. The nitride powder dissolves to provide nitrogen atoms to the solution in a controlled manner, enabling precise control of nitrogen concentration and distribution. This intermediary mechanism prevents local supersaturation and miscellaneous crystal formation while maintaining high growth rates and low resistivity
2Manufacturing precision
If nitrogen concentration in the Si-C solution is increased to achieve low resistivity, then the resistivity decreases, but miscellaneous crystals are generated
Solution Approach 1:
The patent optimizes the nitrogen concentration parameter in the Si-C solution to a specific range (0.01-5 mass%). Within this optimized range, the crystal achieves low resistivity while maintaining uniform structure and avoiding miscellaneous crystal formation. This parameter optimization resolves the contradiction between achieving low resistivity and maintaining crystal uniformity
Solution Approach 2:
The patent implements control of nitrogen concentration through monitoring and adjustment of the nitride addition amount. By controlling the nitrogen concentration within the optimal range, the system prevents local supersaturation and ensures uniform crystal growth, thereby maintaining both low resistivity and high crystal uniformity without generating miscellaneous crystals
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the growth of n-type SiC single crystals at a rapid rate with low resistivity, preventing the formation of miscellaneous crystals and achieving high-quality crystals with resistivity as low as 5 mΩ·cm.
Implementation Method 1
a Si—C solution having a temperature gradient in which the temperature falls from the interior toward the surface
Implementation Method 2
C is dissolved into the molten liquid
Implementation Method 3
dope the SiC single crystal with an n-type dopant
Data Source
AI summary
Provided is a method for producing an n-type SiC single crystal, whereby it is possible to grow an n-type SiC single crystal having a low resistivity at a high speed. A method for producing an n-type SiC single crystal by bringing a SiC seed crystal substrate into contact with a Si—C solution having such a temperature gradient that the temperature gradually decreases from the inside toward the surface, thereby achieving the crystal growth of the n-type SiC single crystal. The method involves adding a nitride to a raw material for forming the Si—C solution or to the Si—C solution.