Room temperature electroluminescence from metal-oxide-semiconductor structures on silicon is observed. The thin oxide is grown by rapid thermal oxidation. With the metal negatively biased, luminescence can be observed. The emission is voltage dependent. For an applied voltage below 5 V, the emission occurs around 1150 nm, approximately corresponding to the Si bandgap energy. For a larger applied voltage, the emission shifts to wavelengths much longer than 1150 nm. The physical reason for the electroluminescence at bandgap energy is attributed to disorder near the Si-SiO2 interface, while the electroluminescence at longer wavelengths could be possibly caused by the c-c or v-v radiative transition.
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