Photoluminescence and electroluminescence of amorphous SiOx films prepared by reactive evaporation of silicon with oxygen

By reactive evaporation of pure silicon in a molecular oxygen atmosphere, thin films of amorphous SiOx can be obtained with 0.7 ⩽ x ⩽ 1.85. The composition and the structure of the films were investigated by energy dispersive X-ray spectroscopy, infrared absorption spectroscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. By a judicious choice of the oxygen pressure, the as-deposited films exhibit visible room-temperature photoluminescence with a peak centered at about 650 nm. At the liquid-nitrogen temperature, some samples also present an electroluminescence peak centered at 740 nm.