Organic vapor sensitivity in a porous silicon device

Abstract

An organic vapor sensitive device using anodized porous silicon has been developed. The device consists of two pn junctions surrounded by the porous silicon layer as a vapor sensing element. The devices show an increase of current for exposure to thousands ppm of organic vapor at room temperature. A high sensitivity is observed for ethanol vapor. The porous silicon combined with the reverse biased pn junction plays an important role for vapor sensing. It is discussed that the adsorption of polar molecules in the vicinity of pn junction induces a ‘soft’ breakdown in the reverse biased pn junction.