Magnetron sputtered Zn-Ta2O5 thin films for electronic, thermoelectric, and optical applications

Abstract

In the current study, the optical and electronic properties of Zn-Ta₂O₅ have been investigated as a potential optoelectronic material. Theoretically, the density functional theory was employed to pure and Zn doped Ta₂O₅ compositions using the Wien2k code. For experimental investigations uniform thin films were fabricated by magnetron co-sputtering technique on the silicon substrate. The optical, thermoelectric, electronic, and morphological properties were studied by relating the outcomes of simulations and experimental results providing the correlation among the findings. Graphs of the total density of states and partial density of states revealed the hybridization between the dopant and host orbitals. The p-d hybridization of O and Ta atoms was shown by the density of states. Structural studies reveal the growth of primary phase identified as orthorhombic Ta₂O_5. The grain growth of the Zn-Ta₂O₅ thin films gradually increase as the Zn content was increased and led to more compact film formation. Zn incorporation improves the thermal transport properties by increasing the Seebeck coefficient and reducing thermal conductivity. Band gap values were reduced by increasing the Zn concentration and recorded value was observed as 3.07 eV for Ta₂O₅ and 1.77 eV for maximum zinc concentration. Optical characteristics are measured in relation to photon energy which shows enhancement by the Zn doping. The outcomes of the current study manifest that these materials provide great potential for thermoelectric and optoelectronic applications.