Heat treatment in 110°C liquid water used for passivating silicon surfaces

We report effective passivation of silicon surfaces by heating single crystalline silicon substrates in liquid water at 110°C for 1 h. High values of photo-induced effective minority carrier lifetime τ_eff were obtained ranging from 8.3×10^-4 to 3.1×10^-3 s and from 1.2×10^-4 to 6.0×10^-4 s over the area of 4 inch sized n- and p-type samples, respectively, while values of τ_eff of initial bare samples were lower than 1.2×10^-5 s. The heat treatment in liquid water at 110°C for 1 h resulted in low surface recombination velocities ranging from 7 to 34 cm/s and from 49 to 250 cm/s for those 4 inch sized n- and p-type samples, respectively. The thickness of the passivation layer was estimated to be approximate only 0.7 nm. Metal-insulator-semiconductor type solar cell was demonstrated with Al and Au metal formation on the passivated surface. Rectified current voltage and solar cell characteristics were observed. Open circuit voltage of 0.49 V was obtained under AM 1.5 light illumination at 100 mW/cm².