VISIBLE-LIGHT EMITTING FROM THE SURFACE-LAYER ON A POROUS LAYER

In the present paper, the cathode luminescence (CL) spectrum of visible light emitting porous silicon (peak at 680nm) was obtained and proved to be similar to the photoluminescence one. The CL was studied by scanning electron microscopy (SEM). The SEM photographs of the surface of the sample show that the CL only emits from the surface layer and there is no CL from the porous layer where the surface layer was moved away. The SEM photographs of the cross-section of the sample show the same result. The above experiments suggest again that the visible luminescence from the porous silicon is from the fluorescent material produced in the surface layer of the porous silicon.