Visible light emission from silicon dioxide with silicon nanocrystals

An electroluminescent MOS structure was developed using silicon wafers covered by thermal silicon dioxide containing silicon nanocrystals. Efficiency of the structure was sufficient for observation to be possible with the naked eye in daylight conditions under DC polarization. Silicon nanocrystals were produced using silicon ion implantation followed by subsequent annealing at 1100 degrees C in a nitrogen atmosphere. Three separate bands of emitted light at wavelengths of similar to 400-500nm (blue), similar to 500-600nm (green), and similar to 650-850 nm (red) were observed and found to be related to specific regions of the implanted silicon concentration profile. For a single energy implant, each of the emitted light bands originated from a separate depth region of the silicon dioxide layer containing silicon nanocrystals. The spectrum of the emitted light was found to depend on the excess silicon concentration profile. For practical applications, the color of the emitted light can be controlled by adjustment of the implantation parameters and MOS structuring process. (c) 2007 Published by Elsevier Ltd.