A supply source for delivery of a CO-containing dopant gas composition is provided. The composition includes a controlled amount of a diluent gas mixture such as xenon and hydrogen, which are each provided at controlled volumetric ratios to ensure optimal carbon ion implantation performance. The composition can be packaged as a dopant gas kit consisting of a CO-containing supply source and a diluent mixture supply source. Alternatively, the composition can be pre-mixed and introduced from a single source that can be actuated in response to a sub-atmospheric condition achieved along the discharge flow path to allow a controlled flow of the dopant mixture from the interior volume of the device into an ion source apparatus.