PURPOSE: To independently control the carbon concentration of a p-type GaAs layer doped with carbon at a high concentration without changing the growing speed of the GaAs layer at the time of growing the GaAs layer.

CONSTITUTION: A GaAs compound semiconductor is grown on a substrate for growing crystal by using the vapor phase epitaxy causing a thermal decomposition reaction by supplying a group III or V gaseous starting material. TEG, an organic metallic compound such as TMAs or TEAs, and TMG are respectively used as the group III gaseous starting material, group V starting gaseous material, and carbon dopant. Requirements for the growth temperature and growth pressure are such that the growth of GaAs is transportation rate- determining when TEG and a group V gaseous starting material are used, and the carrier concentration is at least 1×1020cm-3 or higher when GaAs is grown by using TMG and a group V gaseous starting material. In addition, the growth rate of GaAs when TMG and a group V gaseous starting material are used is ≤1/10 of the growth rate at the time of group III transportation rate-determination. To be specific, the growth temperature is 350-475°C and the pressure is ≤13.3×103Pa.