Oxidation of porous silicon in dry and wet environments under mild temperature conditions

Oxidation behavior of porous silicon under various environments of dry and wet air, and solution with and without appropriate oxidant at mild temperat ures has been investigated. The progress of oxidation was followed by infra red spectroscopy. The presence of water vapor greatly accelerates the oxida tion rate in comparison with the rate in dry air. The oxidized states are c larified with the help of oxidation experiments of partially hydrogen-desor bed porous silicon, which does not contain SiH2 and SiH3 as the hydride spe cies. An oxidation mechanism is proposed to explain that oxidation is accel erated in the presence of water vapor and at the partially hydrogen-desorbe d porous silicon. Further, oxidation behavior of porous silicon in solution containing appropriate oxidant is also investigated. The rate is very rapi d and the oxidation does not produce the back-bond oxidized state of OySiHx in contrast to the oxidation in air.