The diffusion redistribution of hydrogen and oxygen in porous silicon films

The diffusion parameters of H2 and O2 atoms in free-standing porous silicon films were determined by analyzing changes in intensity of Si-H and Si-O absorption peaks with annealing temperature and duration. The films were prepared on n-type Si substrates by anodic etching, followed by detachment by electropolishing. Measurements showed that, in the range 65-185 °C, the temperature dependence of the H2 and O2 diffusion coefficients are described by activation energy of 0.37 and 0.50 eV, respectively. Decrease of intensity of hydrogen-related infrared peak correlates with appropriate decrease of intensity of photoluminescence for films exposed to isothermal annealing. Si-H and Si-H2 related centers are assumed responsible for the photoluminescence.