Si surface passivation by sulfur and reduction of interface defect recombination

Excellent surface passivation of n-type Si is achieved by surface reaction in H₂S at a temperature of 450 - 650°C. X-ray photoelectron spectroscopy (XPS) analysis of the H₂S reacted Si surface shows that effective minority carrier lifetime (τ_eff) increases with increase of S concentration up to ~ 3% and stabilizes thereafter, indicative of an effective passivation by approximately a monolayer S coverage. Numerical fitting of injection level dependent lifetime curves indicate S reduces the interface defect states (D_it) to <; 5×10¹⁰ cm^-2 ev^-1 and introduces a positive passivation charge (Q_pass) of > 1×10¹¹ cm^-2 leading to greatly reduced interface defect recombination.