Electroluminescence from semitransparent Au film/SiO₂/(amorphous-Si/SiO₂) superlattice/p-Si structure

SiO₂ layer/four-period amorphous-Si/SiO₂ superlattices (ASSOSLs) with amorphous-Si layers having 12 thicknesses in a range of 1.0-3.2 nm were deposited on p-Si substrates using the two-target alternation magnetron sputtering technique. Electroluminescence (EL) from semitransparent Au film/SiO₂/ASSOSL/p-Si diodes and from a control diode without any amorphous-Si layer in the ASSOSL has been observed when the applied forward bias exceeded about 5 V; under reverse biases, however, no EL was observed. Every EL spectrum of the Au/SiO₂/ASSOSL/p-Si diodes along with the control one could be decomposed into two Gaussian bands with peak energies of 1.82 and 2.22 eV, and full widths at half maximums of 0.40 and 0.65 eV, respectively; and their intensities and the current swung synchronously with increasing Si layer thickness with a period length being consistent with half a De Broglie wavelength of the carriers. The experimental results indicated that the EL originates mainly from the radiative recombination of electron-hole pairs via two types of luminescence centers with luminescence energies of 1.82 and 2.22 eV in the SiO₂ layers, rather than within the nanometer Si quantum wells in the ASSOSLs.