Trimethylphosphine, (CH3)(3)P, an organic phosphine liquid, has been investigated as a source for P-+(31) ion implantation in silicon using a cold-cathode implantation system. The use of trimethylphosphine has the potential to minimize safety concerns associated with other implantation sources for phosphorous. Using secondary-ion mass spectroscopy and Auger electron spectroscopy analysis the P+, (CH2)(+), and (CH)P+ current peaks were identified. A graphical analysis procedure was then used to predict the other dominant peaks of the beam current spectrum. Using this graphical analysis the dominant species of the beam current spectrum were determined to be (CH3)(+), (CH2)(+), (CH3)2P(+), and (CH3)3P(+). Although the beam current spectrum for (CH3)(3)P was found to be abundant in ionic species, the P+ beam current peak was easily resolved. The P+ peak revealed no carbon, indicating the suitability for silicon device fabrication.