Stable blue light emission from oxidized porous silicon

We have achieved production of porous silicon (PS) that emits blue light at a peak wavelength of 460 nm. On storing it in air for three months, or illuminating it with the 365 nm line of a UV lamp, its photoluminescence intensity and peak wavelength remain stable. With Fourier-transform infrared (FTIR) measurements, we have studied the surface chemical bonds of the PS emitting blue light, and compared its FTIR spectrum with those of the as-prepared PS emitting red-orange light, and those of the processed PS emitting no light We consider that the blue light emission originates from the SiO x layers covering nanoscale silicon units in PS.