Electroluminescence of spark-processed silicon

We have successfully fabricated spark-processed silicon to produce electroluminescence that can be readily seen under semi-dark conditions when about 10V pulses with a duty cycle of 50% sre applied to the sample. The samples were lightly spark- processed. After spark-processing, a layer of semitransparent metal was evaporated onto the surface of the sample as electrode and a layer of Al on the back as ohmic contact. The electroluminescence spectrum is measured with narrow band filters and a Si diode detector plus pre-amplifier. From the spectrum, the peak around 650 nm matches what is seen with naked eye. XPS measurements show that the sample is composed mostly of Si and a few percent of oxygen. FTIR analysis indicates the existence of only Si-O species. At this stage is suspected that the light emission from spark-processed silicon may be due to some kinds of nanostructure, either nanosize silicon or nanosize silicon particles in silicon dioxide or both