Photoluminescence response of gas sensor based on CHx/porous silicon—Effect of annealing treatment

The most spectacular feature of porous silicon (PS) is its ability of emitting very intense visible light at room temperature and to use this light emission as a sensor signal. In this paper, we report the sensitivity of porous silicon photoluminescence (PL) to carbon dioxide and propane gases. A hydrocarbon film has been applied to PS surface to enhance its luminescence since a complete surface passivation is important to suppress or reduce non-radiative recombination centres. The operation sensor effect is based on the variation of the photoluminescence of the CHx/PS region due to the interaction with gaseous substances. Presence of carbon dioxide reduces the PL intensity while propane provokes an opposite behaviour. The PL quenching phenomenon leads itself to interesting optical sensor applications. The annealing effect on the photoluminescence of a p-type CHx/PS has been investigated. The orange light disappears and an intense blue light is obtained. Moreover, the effect of this treatment on the PL response of porous silicon in presence of CO2 and propane gases has also been studied.