Preparation and broadband white emission of Eu-doped thin films based on SiAlON

The optical performance of europium (Eu) doped SiAlON thin films and its preparation by pulsed laser deposition are studied. The undoped SiAlON films show a high refractive index (2.34) close to that of silicon nitride. After doping with Eu the oxygen content increases in the films and leads to the formation of an oxynitride with a refractive index of 1.87 and excellent transparency in the visible-near infrared. Upon excitation at 355 nm the films show a broad band (FWHM of 200 nm) emission in the visible range (400-750 nm) that is associated to the emission of the Eu in the 2+ oxidation state. Enhancement of the emission together with a blue spectral shift has been found when the films are annealed at low temperature (600 °C). These films show promising properties for the development of Si compatible thin films integrated emitters.