Archive Light Emitting Micropatterns of Porous Si Created at Surface Defects P. Schmuki, L. E. Erickson, and D. J. Lockwood Phys. Microscopic Graffiti 7 May 1998 Silicon, the raw material of the microchip revolution, can glow at room temperature. Fundamental questions remain about the material, including the electrochemical process that creates it. Interference patterns like those of a soap film show where a thin layer of silicon has become porous. This demonstration of the technique honors the two institutions that collaborated on the work.
Porous silicon is made by submerging a silicon crystal in an acid solution and applying current.
Just as the spacing between allowed energies of an electron in a box increases with smaller box sizes, the confinement of electron-hole pairs to the silicon crystallites boosts the spacing of their energy levels. Transitions that emit infrared photons in normal silicon, emit in the visible range in porous silicon, and the wavelengths of emission can be tuned by varying the sizes of the crystallites. The results suggest that the pore formation process begins at crystalline defects, rather than at impurities, as some have suggested. All rights reserved.