Photoluminescence and structure of sputter-deposited Zn 2 SiO 4 :Mn thin films

Mn-doped Zn2SiO4 thin films were deposited on Si (100) substrates by radio-frequency (RF) magnetron sputtering. The deposited films were then annealed at temperatures ranging from 600 to 1200 °C in an air ambient for 1 hour. The as-deposited Zn 2 SiO 4 :Mn films exhibited an amorphous structure having a smooth surface and showed no photoluminescence (PL). Annealing at 600 °C was found to have little effect on the properties of the films. The films still remained amorphous with no PL. After annealing at 800 °C, the films were crystallized in a mixture of orthorhombic β -Zn 2 SiO 4 and rhombohedral α -Zn 2 SiO 4 phases. These films showed a PL emission spectrum that could be resolved into two bands, one centered at 520 nm in the green region and the other at 571 nm in the yellow region. The green PL emission originated from the 4 T 1 → 6 A 1 intrashell transition of Mn 2+ ions in the α -Zn 2 SiO 4 phase while the yellow emission was attributed to Mn 2+ ions in β -Zn 2 SiO 4 . The films annealed at and above a temperature of 900 °C exhibited only the α -Zn 2 SiO 4 phase, and the PL spectra of these films showed only the green emission band with a peak maximum at around 523 nm. The PL emission intensity increased with increasing annealing temperature, which was due to the better crystalline quality and the rougher surface morphology of the Zn 2 SiO 4 :Mn films annealed at higher temperatures.