A novel electroluminescent diode with nanocrystalline silicon quantum dots

We have developed an electroluminescent (EL) diode with novel active layers of nanocrystalline silicon (Si) quantum dots. The nanocrystalline Si active layer is fabricated by pulsed laser ablation (PLA) in inert gas ambient. The structure of the EL diodes is semitransparent Pt electrode/silicon nanocrystallite layer/p-type Si/Pt electrode. We have observed visible spectra of not only photoluminescence (PL) around 2.10 eV but also EL around 1.65 eV, at room temperature. The EL diodes show a rectifying behavior. Furthermore, we have found that the EL diodes show strong nonlinear dependence of EL intensity on current density. A possible mechanism of this emission is impact ionization by hot electrons injected through the surface oxide layers and successive radiative recombination.