White Cathodoluminescence Emission from Eu‐Doped SiAlON Thin Films

Abstract

SiAlON materials in thin film configuration are very attractive because their composition can be easily modified from that of silicon dioxide to that of silicon nitride to effectively tune their electrical and optical response, therefore making them suitable for a wide range of optoelectronic devices. In addition, rare‐earth doped SiAlON phosphors in powder configuration are excellent down‐converters to visible light when excited by ultraviolet‐blue photons from light emitting diodes. In this work, the direct excitation by electrons of amorphous nanostructured Eu‐doped SiAlON thin films is explored. XPS analysis shows that the Eu in the films is in its divalent oxidation state (Eu2+), with traces of Eu with a richer oxygen coordination at the film surface. The cathodoluminescence emission from the films is dominated by a wide emission band (FWHM 195 nm) in the visible associated with the Eu2+ 5d to 4f electronic transitions, with a small narrow peak contribution from Eu3+ intra‐4f electronic transitions. Assessment of the CIE color coordinates shows that the spectral emission is close to the pure white. These results show the excellent potential of the Eu‐doped SiAlON films for its implementation in CMOS structures as white light solid state emitters in field emission lamps and displays.