Electroluminescence from Au/(nanoscale Ge/nanoscale SiO₂) superlattices/p-Si

Nanoscale Ge/nanoscale SiO₂ superlattices (SLs) with four periods have been grown using the two-electron-beam alternation evaporating technique. Visible electroluminescence (EL) from the semitransparent Au film/(nanoscale Ge/nanoscale SiO²) SL/p-Si structures was observed when the forward bias exceeded 5 V, and their EL power efficiencies were significantly higher than that of a semitransparent Au film/nanoscale Ge particles embedded SiO₂ film/p-Si structure. The effects of thicknesses of nanoscale Ge layers in the SLs and of annealing temperatures on the EL were studied. It is found that the intensity and position of the major EL peak being located in a range of 640-680 nm vary synchronously, while the EL shoulder around 520 nm remains unchanged in wavelength with increasing Ge layer thickness. The results strongly support the viewpoint that EL originates from the luminescence centers in the SiO₂ layers.