Chopping frequency variation of photoacoustic amplitude from porous silicon

We investigated the possibility of applying photoacoustic (PA) spectroscopy to the study of luminescent porous silicon. Since porous silicon is usuall y formed on a silicon substrate, PA spectroscopy is useful for obtaining th e absorption coefficient of porous silicon without removing the substrate. In this article, we investigated the chopping frequency dependence of the P A signal from porous silicon and showed that the chopping frequency is crit ical for the exclusion of the PA signal from silicon substrate.