THE ROOM-TEMPERATURE OXIDATION OF POROUS SILICON

The room temperature oxidation of porous silicon was studied using iso thermal methods. The oxidation was found to depend on the type of the porous silicon. The microcalorimetric signals from the oxidation of th e p(+)- and n-type porous silicon in dry air were different. In humid air the signals from the oxidation could not be distinguished from the strong signal due to adsorption of water vapour, but when the samples were placed in water similar differences were observed. The reason fo r differences in reactions is discussed. The oxidation in different li quids was also studied. The signal from reactions in methanol and etha nol were found to be 100 times higher than in water. In FTIR studies t he reaction gas produced by reactions between alcohols and the porous silicon, silane (SiH4) was found in the gas. Traces of SiOCH3 and SiOC 2H5 groups were also found in FTIR spectra indicating Si-O-CxHy passiv ation of the surface. (C) 1997 Elsevier Science B.V.