ИСТИНА

Porous silicon nanowire arrays are shown to be used for optical detection of molecular oxygen (O2). The samples were produced by metal assisted chemical etching of heavily boron-doped wafers of crystalline silicon. It was found that the photoluminescence signal from porous silicon nanowires quenched in O2 ambience but restored again in N2 atmosphere, which repeated in several cycles. Electron paramagnetic resonance data demonstrated that number of silicon dangling bonds (Pb-center) increased after O2 adsorption, but then dropped in vacuum. The experimental results are explained by a microscopic model taking into account the reversible charging/recharging of surface defects (Pb-centers) due to the oxygen adsorption/desorption. The obtained results indicate that porous silicon nanowires are prospective for applications as reversible optical gas sensor.