reflectance of incident laser light standardized to incident light as the haze increases the specular surface is degraded the sheet resistivity rs is the inverse of the sheet conductivity of the ingaas layer the deviation of the sheet resistivity in a wafer is represented by the standard deviation u03c3 and the average value rs as u03c3 rs in fig4 shows the surface morphology the sheet resistivity the deviation of the sheet resistivity respectively and contact resistivity of the ingaas layer 32 of the sample 200a according to the prior art and of the super periodic ingaas layer 32b of the sample 100a according to the present invention as shown in fig4 in the super periodic ingaas layer 32b of the present invention a favorable specular surface i e haze u2266 100 ppm that can be applied to an actual device is realized at the growth temperature 450 u00b0 c with no significant increase in the sheet resistivity or deviation of the sheet resistivity although the super periodic ingaas layer of the present invention appears to be inferior to the prior art ingaas layer grown at 400 u00b0 c since it is most important to suppress the contact resistivity the super periodic ingaas layer is superior to the prior art ingaas layer if the contact resistivity is taken into account see fig6 fig8 a and 8 b schematically illustrate.