Field effect surface passivation of SiO2/Si interfaces by heat treatment with high-pressure H2O vapor

We investigated a simple field effect passivation of the silicon surfaces using the high-pressure H2O vapor heating. Heat treatment with 2.1×106 Pa H2O vapor at 260°C for 3 h reduced the surface recombination velocity from 405 cm/s (before the heat treatment) to 38 cm/s for the thermally evaporated SiOx film/Si. Additional deposition of 140 nm-SiOx films (x<2) with a high density of fixed positive charges on the SiO2/Si samples further decreased the surface recombination velocity to 22 cm/s. We also demonstrated the field effect passivation for n-type silicon wafer coated with thermally grown SiO2. Additional deposition of 210 nm SiOx films on both the front and rear surfaces increased the effective lifetime from 1.4 to 4.6 ms. Combination of thermal evaporation of SiOx film and the heat treatment with high-pressure H2O vapor is effective for low-temperature passivation of the silicon surface.