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 , 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 dopant and a halogen is introduced into an 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 dopant ions than would occur if the third source gas were not used .