Influence of supercritical and natural drying methods on structure and properties of porous silicon

We have studied the surface morphology, photoluminescence (PL), Raman spect ra and optical absorption of the porous silicon (PS) samples prepared under supercritical drying (SD) and natural drying (ND) process. The experimenta l results of scan electron microphotograph and Raman spectra show that ther e are obvious differences in microstructure between the SD and ND samples. No crack of the skeleton has been found in the SD sample, but the skeleton of the ND sample has heavily destroyed. Besides, the PL and absorption spec tra of the SD sample are not the same as those of the ND sample.