Electroluminescence with micro-watt output from ultra-small sized Si quantum dots/amorphous SiO 2 multilayers prepared by laser crystallization method

Abstract

We report the fabrication of Si quantum dots (QDs)/SiO 2 multilayers by using KrF excimer laser (248 nm) crystallization of amorphous Si/SiO 2 multilayered structures on ITO coated glass substrates. Raman spectra and transmission electron microscopy demonstrate the formation of Si QDs and the size can be controlled as small as 1.8 nm. After laser crystallization, Al electrode is evaporated to obtain light emitting devices and the room temperature electroluminescence (EL) can be detected with applying the DC voltage above 8 V on the top gate electrode. The luminescent intensity increases with increasing the applied voltage and the micro-watt light output is achieved. The EL behaviors for samples with different Si dot sizes are studied and it is found that the corresponding external quantum efficiency is significantly enhanced in sample with ultra-small sized Si QDs.