PURPOSE: To form a high-quality semiconductor film free of pollution, damage, etc., with dimension accuracy on the order of the size of atom.

CONSTITUTION: The surface of an AlGaAs layer 2 consists of a monomolecular step 3 having a step of 2.8 and a terrace 162 in width covered with As atoms, and the As atoms on the terrace 4 are replaced with nitrogen atoms in order from the end of the monomolecular step by introducing dimethyl hydrazine into the region, and the terrace 4 is distributed into a region 5 covered with nitrogen atoms from the end of monomolecular step 3 and a region 6 kept covered with As atoms. And, GaAs is selectively grown on the region 6 by introducing trimethyl gallium and arsine into the region, so as to form a quantum wire 7.