Visible to near-infrared emission from a porous silicon device

Visible to near-infrared light emission is produced from a porous silicon device under current injection. The visible component appears bright red-orange, and is clearly observed even with room light. The room temperature photoluminescence (PL) spectrum of the porous silicon layer peaks in the red, whereas the electroluminescence (EL) spectrum is extremely broad and peaks in the near-infrared. This structure also exhibits a region of negative differential resistance. The porous silicon emitter is fabricated by initially diffusing phosphorous into a 9 /spl Omega/-cm p-type silicon wafer, creating 50 /spl mu/m wide by 2.5 mm long n+/p junctions.