Electroluminescence from mechanically damaged oxidized silicon

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Abstract
We have found significant electroluminescence (EL), clearly visible in room light, to be produced from lightly oxidized Si wafers, which have been mechanically scratched, or indented with a diamond tip. The EL occurs in the visible and infrared ranges. Undamaged oxidized samples, where the oxide is chemically thinned to allow current from a top contact to pass, also show similar EL. However, damaged Si wafers that have only normal thin or no oxide, show negligible EL. A search for quantum-confined particles in indentation pits by scanning tunneling microscopy does not show any present. The results point strongly to the EL mechanism being related to the damage creating areas of optimum oxide thickness. The results are compared with those from spark-processed and laser-grooved silicon.