Structural and luminescence correlation of annealed Er-ZnO/Si thin films deposited by AACVD process

•ZnO:Er3+ thin films have been successfully deposited using AACVD process with new mixed precursors.•Annealed Polycrystalline films showed good crystallinity in the hexagonal wurtzite phase.•Obtained intense and well resolved luminescence spectra for 2.504 at.% Er doped ZnO film.•For optimum concentration, erbium ions occupy C4v site symmetry in ZnO films.

Er doped ZnO thin films have been synthesized from zinc acetates dihydrate (C4H6O4Zn·2H2O) and Erbium tris (2,2,6,6-tetramethyl-3,5-heptadionate) (Er(TMHD)3) by aerosol assisted chemical vapor deposition AACVD atmospheric pressure technique. Films were deposited in the temperature range of [370–500 °C] on Si (1 1 1) substrate. Nano-disk shaped grains were grown on the top of the film surface. The morphology of the as-deposited films was found to be dependent on the substrate temperature. After annealing in air atmosphere, XRD patterns revealed a highly oriented c-axis Er:ZnO films with hexagonal wurtzite structure without any second phase. Under 488 nm excitation, the intra 4f–4f green emission (2H11/2, 4S3/2 → 4I15/2 transitions) gradually increased with increasing annealing temperature. Also, the local structure of Er changes to a pseudo-octahedral structure with C4v symmetry. The ZnO film with 2.504 at.% Er3+ doping has the best crystalline structure and the best resolved PL spectra. Using 325 nm excitation, all the samples showed an ultraviolet emission centered at 380 nm originating from a near band EDGE emission and a broad band green emission centered at 520 nm from deep levels. The optical response was correlated with crystallinity of the synthesized thin films.