DC/RF magnetron sputter deposition and characterisation of Ca3Si2N2O4:Eu2+ luminescent thin films

Luminescent thin films were deposited using reactive magnetron sputtering of Ca, Si (RF) and Eu (DC) in an Ar/N2 atmosphere. A crystalline Ca3N2Si2O4 phase was detected using XRD analysis. The molar ratio of Ca to Eu in the film was found to be 3:0.3. Luminescence excitation, emission and decay measurements reveal two broad bands of Eu2+ emission with local maxima around 550 nm and 630 nm under UV excitation. The measured luminescence is characteristic for Eu2+ emission in reported Ca3Si2N2O4 phosphors. This was confirmed with time-resolved luminescence decay measurements that show a two component luminescence decay spectrum characterised by time constants of 0.13 μs and 0.56 μs. EDS measurements showed a metal-to-Si ratio of 3:2.4, metal-to-N ratio of 3:1.5 and a metal-to-O ratio of 3:5.1, where (Ca+Eu) is the metal fraction. The overestimation of Si and O and the underestimation of N is caused by the presence of a crystalline, non-luminescent oxide phase. This was confirmed with XRD, where a weak Ca2SiO4 signal was observed.