Electroluminesence from Au/(SiO₂/Si/SiO₂) nanoscale double-barrier/n⁺-Si structure

The (SiO₂/Si/SiO₂) nanoscale double-barrier/n⁺ -Si structures with Si layers of various thicknesses were fabricated by the two-target alternative magnetron sputtering technique. The thicknesses of the Si layers in the structures are from 2 nm to 4 nm with an interval of 0.2 nm. The control samples with Si layers of 0 nm were also made. After these structures were annealed at 600 °C in a N₂ ambient for 30 min, electroluminescence (EL) from the Au/SiO₂/Si/SiO₂/n⁺ -Si structures were observed under reverse biases (n⁺ -Si is biased to positive). It was found that the current and EL intensity synchronously swing with increasing Si layer thickness. All EL spectra of the samples can be decompounded into two Gaussian luminescent spectra with peaks at 1.85 eV (670 nm) and 2.26 eV (550 nm). Analysis of experimental results indicates that the EL orginates from the recombination of electrons and holes, which are produced in an avalanche process in the Au/(SiO₂/Si/SiO₂) nanoscale double-barrier/n⁺ -Si structure, via luminescence centers in the SiO₂ layers.