Toward a High Efficiency Siliocn Solar Cells-Simplified Cell Processing using Paste Contained Phosphorous Compounds

In this study, we present the result of preliminary investigations on the use of selective phosphorous doping and contact opening process in crystalline silicon solar cells. Typical emitter sheet resistance used in a screen-printing metallization process is 30-50 Ohm/sq. Screen printing drastically affects the design of the emitter: it must be very highly doped to decrease the high-contact resistance and not very shallow so that it is not perforated during paste firing, which would short-circuit the junction. Therefore we made improvement involves making separate diffusions for the different regions since the requirements are so different: a heavily doped and thick region under the contacts, a thin and lowly doped region under the passivating layer. Furthermore we opened the metal contact area to make a narrow grid lines simultaneously. As a result we could increase fill factor and reduce contact resistance by industrial process