Influence of Tm₂O₃ doping on structural and electrical properties of ZnO

Abstract

In this study, Tm₂O₃-doped ZnO powder system was synthesized in the stoichiometric range of 1–10 mol % by solid state method. Produced samples were characterized by XRD and monophase samples, which were indexed as hexagonal (wurtzite) structure, determined by using XRD data. The limit solubility of Tm₂O₃ in the ZnO lattice is determined to be 4 mol % (after heating at 1000 °C), and beyond 4 mol % the impurity phase was found as cubic-Tm₂O₃. For monophase Tm₂O₃–ZnO binary system (synthesized at 1000 °C), the lattice parameters a and c increased with Tm₂O₃ concentration. Electrical conductivity of undoped ZnO and monophase samples were measured using the four probe method. The electrical conductivity values of undoped ZnO and 4 mol % Tm₂O₃-doped ZnO samples (synthesized at 1000 °C) were found to be 8.7 × 10⁻⁷ and 3.1 × 10⁻⁶ Ω⁻¹ cm⁻¹, respectively, at 100 °C and 0.03 and 3.39 Ω⁻¹ cm⁻¹, respectively, at 1000 °C. Also, activation energy of monophase samples (synthesized at 1000 °C) was calculated. UV/Vis absorption and PL emission spectras of undoped and all doped ZnO samples were measured.