Diffusion of tin into from a doped source layer has produced average carrier concentrations twice as high as those previously reported in the literature for diffusions from such films. The average carrier concentration in the diffused layers was for junctions 1 to 2 µm deep. The surface concentration appears to be nearly constant during the first hour of diffusion at 1050°C and decreases due to source film depletion. Carrier concentrations in the diffused layers were measured with both Hall effect and infrared reflectivity techniques.