Sensitivity of porous silicon photoluminescence to low concentrations of CH4 and CO

In this paper we report the sensitivity of porous silicon photoluminescence (PL) to diluted mixtures of methane and carbon monoxide in synthetic air. We also investigate the separate effect of synthetic air, purified nitrogen and relative humidity on both photoluminescence and conductance (G). Porou s silicon samples have been prepared from n-type silicon substrates. We fin d that PL intensity and G decrease in synthetic air with respect to their v alues in N-2. Presence of carbon monoxide reduces the PL intensity while me thane provokes the opposite behaviour. The dependence of the PL spectra on methane and carbon monoxide concentrations has been investigated. The obser ved effects can be related to gas induced modifications in porous surface a nd suggest that porous silicon can be employed in gas sensor technology.