Dual-Color Electroluminescence (λ ≈ 450 nm and 650–700 nm) From a Silicon-Based Light Source

摘要

In this letter, bright “purple” electroluminescence is observed from a multilayer stack with thin amorphous silicon $(alphahbox{-Si})/hbox{SiO}_{2}$, due to the dual-color light emissions in blue and red. Under photoexcitation, the blue emission is negligible compared with the long wavelength red emission and is only present weakly after anneal in $ hbox{N}_{2}$ exceeding 900 $^{circ}hbox{C}$. However, under electrical excitation, the blue becomes obviously visible and shows faster increasing rate with increased carrier injection than the red. From analysis of the samples with different $alphahbox{-Si}$ thicknesses (2–7 nm), the red emission is deemed to have resulted from the quantum-confinement effect within the thin $alphahbox{-Si}$ layers, whereas the blue emission is speculated to have originated from the $ hbox{Si/SiO}_{2}$ interfacial defects.