An apparatus and methods of improving the ion beam quality of a halogen-based source gas are disclosed. Unexpectedly, the introduction of a noble gas, such as argon or neon, to an ion source chamber may increase the percentage of desirable ion species, while decreasing the amount of contaminants and halogen-containing ions. This is especially beneficial in non-mass analyzed implanters, where all ions are implanted into the workpiece. In one embodiment, a first source gas, comprising a processing species and a halogen is introduced into a ion source chamber, a second source gas comprising a hydride, and a third source gas comprising a noble gas are also introduced. The combination of these three source gases produces an ion beam having a higher percentage of pure processing species ions than would occur if the third source gas were not used.