Correspondence between sheet resistance and emitter profile of phosphorus diffused emitters from a spray-on dopant

The evolution of the emitter sheet resistance upon phosphorus in-diffusion from a spray-on dopant has been studied in the temperature range 840-990 /spl deg/C. In complement with investigations of emitter diffusion profiles, by both electrochemical capacitance-voltage profiling and secondary ion mass spectrometry, we find that the sheet resistance is determined directly by the depth of the flat plateau near the surface in profiles of electrically active phosphorus. Thus, with respect to sheet resistance, an emitter can be regarded as a constant concentration abrupt box layer, with thickness and concentration specified by the flat plateau, irrespective of the actual profile at lower concentrations. Therefore, independent optimization of the emitter profile at lower concentrations is enabled.