Effect of POCl3 Bubbler Temperature on Solar Cells Emitter Characteristics

The effect of POCl3 bubbler temperature on silicon n+/p solar cells emitter characteristics is investigated in this paper. By increasing the bubbler temperature, calculations and secondary ion mass spectroscopy (SIMS) characterization showed that the amount of phosphorus entering the diffusion tube has significantly increased. On the contrary, emitter sheet resistances remain constant. This was confirmed and explained by emitters depth profiling of the electrically active phosphorus. Besides that, the minority carrier lifetime measured by means of QSSPC technique decreased indicating that the excess of phosphorus deposited on emitter surface degrades the emitter electrical performance. The same trend has been observed for the implied-Voc. From 632 mV at 15°C the implied Voc decreased to 602 mV at 26°C. In conclusion, we have shown that the temperature of the POCl3 bubbler is also an important parameter that controls the emitter properties.