Pulsed laser deposition of zinc vanadates from a ZnV₂O₆ target

Zinc vanadate thin films, which have the property of band gap tunability together with interesting optical and electrical properties, are excellent candidates for optoelectronic applications such as solar cells. But so far, no reports on thin films deposition of zinc vanadates exist in literature. In the present work, zinc vanadate compounds were grown on glass substrates at room temperature by pulsed laser deposition. A polycrystalline ZnV₂O₆ target synthesized by melt quenching was used for the ablation process. The physical properties of the films were analyzed as a function of density and the mean kinetic energy of ions in the plasma. As-deposited films were amorphous, and after annealing at 500 °C in air, the crystalline structure of the samples changed depending on the plasma density. Raman spectroscopy measurements showed the presence of several vibrational modes in different regions of the annealed samples, indicating the presence of different crystalline phases. The band gap values were 2.77 and 2.82 eV for the as-deposited samples and 3.17, 3.09, and 1.73 eV for the heat treated cases. As-grown samples presented a broad luminescence band in the visible region of the spectrum with features that depended on the plasma density.