Tailored emitter ion-implanted silicon solar cells

Phosphorus ions were implanted into silicon single crystals at 10 keV under channelling conditions; this was followed by a 40 keV random implantation to obtain tailored emitters for solar cells. The implanted layers were annealed either by using an electron gun especially designed to perform heat treatments on semiconductor materials or by furnace treatments at 650 or 750°C for 30 min. Electrical activity profiles, spectral response and cell and diode current-voltage characteristics were measured, and a one-dimensional computer model was used to correlate the cell's performance with the physical characteristics of the emitter layers; profile tailoring and residual damage after annealing were specifically analysed.