An investigation of oxidised porous silicon by infrared spectroscopy

The oxidation of porous silicon has been studied mainly by optical spectrometry and AFM (Atomic Force Microscopy). The annealing behaviour of the Si-H-2-, Si-H and Si-O-Si-related IR bands were investigated for the range 20-500 degrees C at atmospheric pressure. The study is devoted to the process of hydrogen and oxygen competition during the porous silicon oxidation. We found that at 200 degrees C at atmospheric pressure the lifetime of the Si-H-2 bond is about 4 min; for Si-H it is estimated at 20 min. The increase in Si-O absorption at 1 100 cm(-1) indicated an activation energy of 5.1 kcal mol(-1). UV-Vis spectrometry and AFM were used to obtain information about the topology of the porous silicon surface. Comments on some links between the Si-O-Si band profile and the geometry of the oxidised silicon skeleton are included. (C) 1997 Elsevier Science B.V.