THERMAL-OXIDATION OF FREESTANDING POROUS SILICON FILMS

We have studied the thermal oxidation of free-standing porous silicon films from room temperature to 730 degrees C with a differential scann ing calorimeter and a thermogravimeter. We have observed three differe nt thermal oxidation processes for the porous silicon. The change of e nthalpy (Delta H) and activation energy (E(a)) for the first reaction has been calculated. The oxidation of a fresh sample has been compared with those of aged samples, which were stored in dry relative humidit y (RH 0%), humid (RH 100%) and normal (RH 25%-35%) laboratory air atmo spheres. We also used Fourier transform infrared spectroscopy to clari fy the bonds for each process. (C) 1997 American Institute of Physics.