Effect of Reduction Annealing on the Structural and Electrical Properties of Er-Doped ZnO Thin Films

Zinc oxide (ZnO) is one of the most significant functional materials with a wide direct band gap and large exciton binding energy which make it extremely promising. In this study, we investigate the effects of reduction annealing on the structural and electrical properties of 3% Er-doped Zinc Oxide thin films. The films were deposited on Si/SiO₂-boron-doped p-type substrates under a vacuum pressure of 2.5*10^-2 mbar via pulsed laser deposition. X-ray diffraction showed nanocrystalline structures with a favored (002) plane orientation, reduction annealing created highly crystalline hexagonal (Wurtzite) structure with smaller unit cell volume. The hexagonal structure was validated by Raman Spectroscopy. Band gap reduction from 3.37 eV to 3.28 eV was observed using UV-Vis’s spectroscopy. Preliminary field-effect transistor (FET) measurements indicated that the annealed samples retained their semiconducting behavior, as confirmed by the I_DS vs V_DS characteristics demonstrating effective structural and band gap tuning through reduction annealing.