There is provided a high quality epitaxial water on which the density of microscopic defects in the epitaxial layer is reduced to keep the GOI thereof sufficiently high and to reduce a leakage current at the P-N junction thereof when devices are incorporated, to thereby improve the yield of such devices. In an epitaxial wafer obtained by forming an epitaxial layer on a substrate, the density of IR laser scatterers is 5.times.10.sup.5 pieces/cm.sup.3 or less throughout the epitaxial layer.