Improvement of SiO₂ Properties and Silicon Surface Passivation by Heat Treatment with High-Pressure H₂O Vapor

Abstract

Heat treatment with high-pressure H 2 O vapor was applied to improve the properties of SiO x ( x <2) films formed by vacuum evaporation, for passivation of the silicon surface. Heat treatment at 340–420 °C changed SiO x films into SiO 2 films with an Si–O–Si bonding network similar to that of thermally grown SiO 2 films. The densities of interface trap states and fixed positive charges were reduced to 6.5×10 10 cm -2 eV -1 and 2.5×10 11 cm -2 , respectively, after heat treatment at 340 °C with 2.4×10 6 -Pa–H 2 O 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.