Device for forming diamond film etc. and method therefor

A device for forming at least a diamond film on a surface of a substrate, the device comprising:

• a container configured to hold a raw material liquid and to place the substrate in the raw material liquid;
• an electrode part comprising a positive electrode and a negative electrode and configured to generate a plasma in the raw material liquid;
• a raw material gas supply part and a carrier gas supply part, each of the raw material gas supply part and the carrier gas supply part being connected to the electrode part,
• wherein a raw material gas comprising at least a carbon source for forming the at least one diamond film on the surface of the substrate is provided by the raw material gas supply part;
• and
• a power source configured to apply a voltage to the electrode part,
• wherein the power source is a direct current power source, and the electrode part further comprises an adjunctive member, and the adjunctive member is attached to an electrode at a plasma generation region of the electrode part, and
• wherein a part of the adjunctive member is melted to be an impurity supply source member at the plasma generation region.