PURPOSE: To reduce the interfacial contact resistivity with a second semiconductor layer to be regrown by delta-doping the cleaned surface of a first semiconductor layer after the surface of the first semiconductor layer is cleaned by hydrogen plasma.

CONSTITUTION: When a wafer A is loaded into the epitaxial chamber of a compound semiconductor vapor-phase epitaxial apparatus 18 having ECR plasma generator and heated to about 300°C and then hydrogen plasma 17 generated by the ECR plasma generator is irradiated to the wafer for about 5 minutes, cleaning before regrowth in a p-type GaAs layer 12 is ended. The type GaAs layer 12 having ended cleaning is delta-doped with a p-type conductive impurity, e.g. Be, through the opening of the layer 12 and a p-type GaAs layer 14 having higher concentration than the p-type GaAs layer 12 is regrown. At the time of this regrowth, the impurity delta-doped in the interfacial part of each semiconductor layer is diffused and the carrier concentration of a depletion layer generated at the point of time of cleaning is recovered effectively so that the contact resistivity in the regrowth interface is reduced consequently.