Voltage-controlled electroluminescence from SiO2 films containing Ge nanocrystals and its mechanism
Luminescent SiO2 films containing Ge nanocrystals are fabricated by using Ge ion implantation, and metal–oxide–semiconductor structures employing these films as the active layers show yellow electroluminescence (EL) under both forward and reverse biases. The EL spectra are strongly dependent on the applied voltage, but slightly on the mean size of Ge nanocrystals. When the forward bias increases towards 30 V, the EL spectral peak shifts from 590 nm to 485 nm. It is assumed that the EL originates from the recombination of injected electrons and holes in Ge nanocrystals near the Si/SiO2 interface, or through luminescent centers in the SiO2 matrix near the SiO2/metal interface. The mismatch of the injection amounts between holes and electrons results in the low EL efficiency.
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