SiC Single Crystal Resistivity Reduction via Al-B Doping
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Solution Overview
Problem
Existing methods for producing p-type SiC single crystals using solution processes fail to achieve sufficiently low resistivity, limiting their application in high-voltage electrical systems.
Innovation Solution
A method involving a Si-C solution with Al and B, where the Al content is 10 at% or greater and B content is between 0.00 and 1.00 at%, applied with a temperature gradient decreasing from the interior to the surface, to grow p-type SiC single crystals with resistivity ranging from 9 to 29 mΩ·cm and a growth thickness of 1 mm or greater.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solution processes are used to produce p-type SiC single crystals, then defect reduction is achieved, but resistivity remains too high for ultra-high voltage-resistant elements
Solution Approach 1:
The patent changes the chemical composition parameters of the Si-C solution by adding specific amounts of Al (10-30 at%) and B (0.01-1.00 at%), which fundamentally alters the doping mechanism and achieves resistivity of 9-29 mΩ·cm, resolving the contradiction between crystal quality and resistivity control
Solution Approach 2:
The patent creates a composite doping system combining Al and B in the Si-C solution, where Al provides p-type doping and B enhances the doping efficiency, achieving synergistic effect that produces ultra-low resistivity while maintaining high crystal quality through solution process
2Manufacturing precision
If Al is added to Si-C solution to reduce resistivity, then p-type doping is achieved, but resistivity remains insufficiently low
Solution Approach 1:
The patent introduces B as an intermediary element that enhances the doping effectiveness of Al. B adds to the supersaturation of the Si-C solution and promotes Al incorporation into the crystal lattice, achieving resistivity reduction to 9-29 mΩ·cm while maintaining high doping effectiveness
Solution Approach 2:
The patent optimizes the Al concentration parameter to 10-30 at% in the Si-C solution, which is significantly higher than conventional doping levels, combined with B addition to achieve the target resistivity range through controlled supersaturation during crystal growth
3Power
If sublimation processes are used to grow SiC single crystals, then high output and high frequency are achieved, but micropipe defects and stacking faults occur
Solution Approach 1:
The patent replaces the gas-phase sublimation process with a liquid-phase solution process, substituting the mechanical vapor transport mechanism with a chemical dissolution-precipitation mechanism, thereby eliminating micropipe defects and stacking faults while maintaining the ability to produce high-power semiconductor materials
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 results in p-type SiC single crystals with significantly lower resistivity, up to 1/200 of conventional p-type SiC single crystals, while maintaining stable crystal growth and avoiding defects like micropipe defects.
Implementation Method 1
Solution processes are processes in which molten Si or molten Si in which a metal other than Si is melted is formed in a graphite crucible, C is dissolved into the molten liquid, and a SiC crystal layer is deposited and grown on a seed crystal substrate set in the low temperature zone
Implementation Method 2
a Si—C solution having a temperature gradient such that a temperature of the Si—C solution decreases from an interior of the Si—C solution toward a surface of the Si—C solution
Implementation Method 3
a Si—C solution having a temperature gradient such that a temperature of the Si—C solution decreases from an interior of the Si—C solution toward a surface of the Si—C solution
Data Source
AI summary
A low-resistance p-type SiC single crystal containing no inclusions is provided. A method for producing a SiC single crystal in which a SiC seed crystal substrate is contacted with a Si—C solution having a temperature gradient such that a temperature of the Si—C solution decreases from an interior of the Si—C solution toward a surface of the Si—C solution, to grow the SiC single crystal, wherein the Si—C solution comprises Si, Cr, Al and B, and wherein the Al is comprised in the Si—C solution in an amount of 10 at % or greater, based on the total of the Si, Cr, Al and B, and the B is comprised in the Si—C solution in an amount of greater than 0.00 at % and no greater than 1.00 at %, based on the total of the Si, Cr, Al and B.