Advanced Physical Research

Undoped and Zr-incorporated In₂O₃ nanostructured thin films were fabricated by pulsed laser deposition under ambient-temperature conditions, followed by post-deposition annealing at 250 °C. In this study, the investigation of three different films has been conducted: pure In₂O₃ (F1), In₂O₃ doped with 2 at.% of Zr (F2) and In₂O₃ doped with 5 at.% of Zr (F3). The study of crystal structure using XRD technique confirms formation of bixbyite type of In₂O₃ with nanocrystalline structure and broadening of diffraction maxima. The calculations of average grain size give the following results: 10.3 nm (pure In₂O₃), 11.77 nm (2 at.% Zr) and 9.69 nm (5 at.% Zr). FESEM technique shows homogeneous surfaces, absence of cracks and well-developed nanostructure. Improvement in grain interconnections is achieved for 2 at.% Zr. As seen from optical analysis, both absorbance and the absorption coefficient reduce when the content of Zr increases. The increase of transmittance is observed in visible range of spectrum. Thus, AVT values are 44.7% and 61.0% for undoped film and 5 at.% Zr-doped film, respectively. Blue shifts in optical spectra are found in accordance with increasing of Zr concentration. Moreover, optical band gaps increase from 2.9 eV (undoped) to 3.0 eV (2 at.% Zr) and 3.1 eV (5 at.% Zr) according to Tauc plots. Qualitatively, these results can be explained by Burstein–Moss effect due to decreasing of defect states; however, electrical measurements are needed to confirm it. It can be estimated that average film thickness varies from about 200 to 230 nm. The 2 at.% Zr-doped film showed the best structural and morphological balance, whereas the 5 at.% Zr-doped film exhibited the highest optical transmittance. Overall, these results demonstrate the perspective of use of Zr-doped In₂O₃ thin films as transparent oxides and optoelectronic materials, which were prepared at relatively low temperatures; nevertheless, it needs further investigation of electrical properties.