An n-Inp buffer layer, a GRIN-SCH-MQW active layer, and a p-InP spacer layer are laminated on an n-InP substrate. A back of the plunger may be formed at an angle and to include a retention guide, the retention guide partly over the sphere such that the sphere may be in contact with the back of the plunger and the retention guide. The dispenser socket is provided with a vent tube that projects upwardly from an air relief port in the socket floor. Then, based on these respective grasped total amounts, a ration of the total improvable steam loss mount relative to a total unknown steam amount Qx which is a difference between the total receiving steam amount Qi and the total necessary steam amount Qx is obtained as an improvable unknown steam ratio Kts. Dopants may be introduced into the SiGe and silicon-carbon regions by in-situ doping or by ion implantation.