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Abstract

A silicon wafer contains: a silicon substrate; a first epitaxial layer on the silicon wafer, wherein the absolute value of the difference between donor and acceptor concentrations is .gtoreq.1.times.10.sup.18 atoms/cm.sup.3; a second epitaxial layer above the first epitaxial layer, whose conductivity type is the same as the first epitaxial layer, wherein the absolute value of the difference between donor and acceptor concentrations is .ltoreq.5.times.10.sup.17 atoms/cm.sup.3; wherein, by doping a lattice constant adjusting material into the first epitaxial layer, the variation amount ((a.sub.1-a.sub.Si)/a.sub.Si) of the lattice constant of the first epitaxial layer (a.sub.1) relative to the lattice constant of the silicon single crystal (a.sub.Si) as well as the variation amount ((a.sub.2-a.sub.Si)/a.sub.Si) of the lattice constant of the second epitaxial layer (a.sub.2) relative to the lattice constant of the silicon single crystal (a.sub.Si) are controlled to less than the critical lattice mismatch.

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First Claim