Photoluminescence in laser ablated nanostructured indium oxide thin films

Nanocrystalline indium oxide films have been deposited using pulsed laser ablation technique at different substrate temperatures and the films are post-annealed at different temperatures. The structural, optical and electrical properties of the films are investigated by XRD, SEM, AFM, UV–vis spectra, photoluminescence spectra and electrical conductivity measurements. X-ray diffractograms of the as-deposited and post-annealed films A–C show that films are amorphous at lower substrate temperatures and transform to mixture of amorphous and crystalline phases. The grain size determination based on Debye Scherrer's formula shows that the average grain size of the crystallites in the films ranges from 6 to 32 nm. Dislocation density, biaxial strain, lattice strain and lattice stress of the films are also calculated. SEM micrographs show that all the films are densely packed with the crystallites in the nanodimensions. SEM images show porous nanocrystalline nature for the films of samples B and C which make them suitable for gas sensing. The as-deposited samples show decrease in resistivity with increase in substrate temperature and the lowest resistivity obtained is 6.6 × 10−5 Ω m for the as-deposited films at substrate temperature 773 K. Efficient photoluminescence emission is observed in all the films and this can be attributed to higher values of rms surface roughness exhibited by these films. In2O3 films exhibit a PL emission property in the UV region at room temperature which suggests possible applications in nanoscale optoelectronic devices in the future.