High-pressure H2O vapor heating used for passivation of SiO2/Si interfaces

High-pressure H2O vapor heating was applied to oxidation of SiOx (x<2) films formed on silicon substrates at room temperature by thermal evaporation in vacuum, in order to improve properties of SiOx/Si interfaces for passivation of silicon surfaces. The SiOx films were oxidized with an activation energy of 0.035 eV. The spin density of unpaired electron decreased from 2.3×1017 to 1.4×1015 cm−3 by the heat treatment at 260°C with 2.1×106 Pa H2O vapor for 3 h. The surface recombination velocity for excess carriers decreased from 405 (as deposited SiOx film) to 13 cm/s. There was no change in the surface recombination velocity after keeping the samples at an atmospheric pressure and at room temperature for 8000 h. Suitable passivation of silicon surface was achieved by simple heating with high-pressure H2O vapor at low temperature.