SINGLE-CRYSTAL SILICON-CARBIDE SUBSTRATE AND POLISHING SOLUTION
The present invention relates to a single-crystal silicon-carbide substrate provided with a principal surface having an atomic step-and-terrace structure containing atomic steps and terraces derived from a crystal structure, in which the atomic step-and-terrace structure has a proportion of an average line roughness of a front edge portion of the atomic step to a height of the atomic step being 20% or less.
1 . A single-crystal silicon-carbide substrate provided with a principal surface having an atomic step-and-terrace structure comprising atomic steps and terraces derived from a crystal structure, wherein the atomic step-and-terrace structure has a proportion of an average line roughness of a front edge portion of the atomic step to a height of the atomic step being 20% or less.
2 . The single-crystal silicon-carbide substrate according to claim 1 , wherein the principal surface is a surface on which a crystal is to be epitaxially grown to form a silicon-carbide semiconductor layer or a gallium-nitride semiconductor layer.
3 . A polishing solution for chemically and mechanically polishing a principal surface of a predetermined surface direction of a single-crystal silicon-carbide substrate, such that the principal surface has an atomic step-and-terrace structure comprising atomic steps and terraces derived from a crystal structure, and that the atomic step-and-terrace structure has a proportion of an average line roughness of a front edge portion of the atomic step to a height of the atomic step being 20% or less,
wherein the polishing solution comprises an oxidizing agent containing a transition metal having oxidation-reduction potential of 0.5V or more, and water, and does not contain an abrasive.
4 . The polishing solution according to claim 3 , wherein the oxidizing agent is permanganate ions.
5 . The polishing solution according to claim 4 , wherein the permanganate ions is contained in an amount of 0.05% by mass or more and 5% by mass or less based on the total amount of a polishing agent.
6 . The polishing solution according to claim 3 , having pH of 11 or less.
7 . The polishing solution according to claim 4 , having pH of 11 or less.
8 . The polishing solution according to claim 5 , having pH of 11 or less.
9 . The polishing solution according to claim 6 , having pH of 5 or less.
10 . The polishing solution according to claim 7 , having pH of 5 or less.
11 . The polishing solution according to claim 8 , having pH of 5 or less.