Optimization of electro-luminescence performance of silicon quantum dots based light-emitting-diode

Silicon quantum dots based light-emitting-diode are prepared using SiO_x~1 film as active layer and different materials as transparent electrode. SiO_x film is deposited onto p-type Si substrate by e-beam evaporation and then annealed to obtain Si nano-crystals (nc-Si) embedded in SiO₂. TCO materials, such as indium-tin-oxide (ITO), aluminum doped zinc oxide (AZO), and gallium doped zinc oxide (GZO), are evaporated on to the annealed SiO_x film and used to be transparent electrode layer as well as n-type semiconductor of the LED. The I-V measurements and electro-luminescence are performed. The LED using 100 nm SiO_x~1.1 as active layer shows a low turn-on voltage (<5 V). The increase of the thickness of SiO_x layer leads to an augmentation of turn-on voltage which is possibly related to the tunneling effect. EL spectrum of the sample using ITO as electrode is centered at about 600 nm (orange light). Influences of the TCO layer including thickness, material, and thermal treatment are investigated.