Visible electroluminescence from silicon nanocrystals embedded in amorphous silicon nitride matrix

Visible electroluminescence from silicon nanocrystals (Si-NCs) embedded in amorphous silicon nitride $\left(a\text{‐}\mathrm{Si}{\mathrm{N}}_x\right)$ films has been observed. The $\mathrm{Si}\text{‐}\mathrm{N}\mathrm{C}∕a\text{‐}\mathrm{Si}{\mathrm{N}}_x$ films were deposited by evaporating silicon from electron gun into the inductively coupled plasma of nitrogen. The density of Si-NCs in the $a\text{‐}\mathrm{Si}{\mathrm{N}}_x$ matrix was around ${10}^{12}{\mathrm{cm}}^{-2}$ . Strong room temperature photoluminescence was observed in 2.8 and $3.0\mathrm{eV}$ , different from literature values. The electroluminescence (EL) devices were fabricated with $\mathrm{Si}\text{‐}\mathrm{N}\mathrm{Cs}∕a\text{‐}\mathrm{Si}{\mathrm{N}}_x$ film as the active layer using the Al or $\mathrm{Ca}∕\mathrm{Ag}$ cathode and the indium tin oxide anode. Through tunneling, the electrons and holes were respectively injected from the cathode and anode into Si-NCs and confined within Si-NCs for light emission by the high band gap $a\text{‐}\mathrm{Si}{\mathrm{N}}_x$ matrix. For the device with $\mathrm{Ca}∕\mathrm{Ag}$ cathode, the turn-on voltage was as low as $10\mathrm{V}$ and the EL efficiency was about $1.6\times {10}^{-1}$ $\mathrm{Cd}∕\mathrm{A}$ . The EL spectra consisted of two broad peaks centered around 2.5 and $2.8\mathrm{eV}$ . Our results demonstrate that $\mathrm{Si}\text{‐}\mathrm{N}\mathrm{Cs}∕a\text{‐}\mathrm{Si}{\mathrm{N}}_x$ nanocomposite films have potentials to be fabricated into electroluminescence devices using the low work function cathode.