An impurity doped SiC substrate 1 and SiC thin film 2 are irradiated with a laser light 5 having a wavelength longer than such a wavelength that a band edge absorption of a semiconductor is caused. The wavelength of the laser light 5 may be such a wavelength that an absorption is caused by a vibration by the bond of an impurity element and an element constituting the semiconductor, for example, a wavelength of 9 &mgr;m to 11 &mgr;m. Specifically, in the case where Al is doped in SiC, the wavelength of the laser light 5 may be within the range of 9.5 &mgr;m to 10 &mgr;m.