The Efficient Visible Light from the Surface Layer of Porous Silicon

The visible cathodolumincscence (CL) spectrum of the visible light emitting porous silicon(peaked at 680nm) was obtAlNed and proved to be similar to the photoluminescence one. The sourceof CL was detected by the scanning electron microscopy (SEM). The SEM microphotographes ofthe surface of the sample shows that the CL only emits from the surface layer and there is no CLfrom the porous layer where the surface layer dropped off. The SEM microphotogrophes on thecross section of the sample shows the same result. The above experiments suggest agAlN that thevisible luminescence from the porous silicon is from the fluorescent material in the surface layer ofthe porous silicon.