Emergence and Evolution of Crystallization in TiO2 Thin Films: A Structural and Morphological Study

Nanomaterials

Maria Principe¹  Riccardo DeSalvo¹  Giovanni Carapella²  Fabrizio Bobba²  Veronica Granata²  Ofelia Durante²  Cinzia Di Giorgio²  Francesco Chiadini³  Vincenzo Pierro³  Rosalba Fittipaldi³  InnocenzoM. Pinto³  Vincenzo Fiumara³  Joshua Neilson³  Franco Dinelli⁴  Antonio Vecchione⁵ 

[1] Department of Engineering, DING, University of Sannio, 82100 Benevento, Italy;Department of Physics “E.R. Caianiello”, University of Salerno, 84084 Fisciano, Italy;National Institute of Nuclear Physics (INFN), Sezione di Napoli Gruppo Collegato di Salerno, 80126 Napoli, Italy;National Research Council-National Institute of Optics, CNR-INO, 56124 Pisa, Italy;National Research Council-SuPerconducting and Other INnovative Materials and Devices Institute (CNR-SPIN), University of Salerno, 84084 Fisciano, Italy;

关键词: thin films;    TiO₂ anatase;    crystallization;    surface imaging;    phonon lifetime;   

DOI  :  10.3390/nano11061409

来源: DOAJ

【 摘 要 】

Among all transition metal oxides, titanium dioxide (TiO₂) is one of the most intensively investigated materials due to its large range of applications, both in the amorphous and crystalline forms. We have produced amorphous TiO₂ thin films by means of room temperature ion-plasma assisted e-beam deposition, and we have heat-treated the samples to study the onset of crystallization. Herein, we have detailed the earliest stage and the evolution of crystallization, as a function of both the annealing temperature, in the range 250–1000 °C, and the TiO₂ thickness, varying between 5 and 200 nm. We have explored the structural and morphological properties of the as grown and heat-treated samples with Atomic Force Microscopy, Scanning Electron Microscopy, X-ray Diffractometry, and Raman spectroscopy. We have observed an increasing crystallization onset temperature as the film thickness is reduced, as well as remarkable differences in the crystallization evolution, depending on the film thickness. Moreover, we have shown a strong cross-talking among the complementary techniques used displaying that also surface imaging can provide distinctive information on material crystallization. Finally, we have also explored the phonon lifetime as a function of the TiO₂ thickness and annealing temperature, both ultimately affecting the degree of crystallinity.

【 授权许可】

Unknown