Improvement of SiO 2 Properties and Silicon Surface Passivation by Heat Treatment with High-Pressure H 2O Vapor

Heat treatment with high-pressure H2O vapor was applied to improve the properties of SiOx (x<2) films formed by vacuum evaporation, for passivation of the silicon surface. Heat treatment at 340–420 °C changed SiOx films into SiO2 films with an Si–O–Si bonding network similar to that of thermally grown SiO2 films. The densities of interface trap states and fixed positive charges were reduced to 6.5×1010 cm-2eV-1 and 2.5×1011 cm-2, respectively, after heat treatment at 340 °C with 2.4×106 -Pa–H2O vapor for 3 h. The heat treatment reduced the recombination velocity for the electron minority carriers from 1200 cm/s (as fabricated) to 140 cm/s.