Durante Ofelia, Di Giorgio Cinzia, Granata Veronica, Neilson Joshua, Fittipaldi Rosalba, Vecchione Antonio, Carapella Giovanni, Chiadini Francesco, DeSalvo Riccardo, Dinelli Franco, Fiumara Vincenzo, Pierro Vincenzo, Pinto Innocenzo M, Principe Maria, Bobba Fabrizio
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.
Nanomaterials (Basel). 2021 May 26;11(6):1409. doi: 10.3390/nano11061409.
Among all transition metal oxides, titanium dioxide (TiO) 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 TiO 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 TiO 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 TiO thickness and annealing temperature, both ultimately affecting the degree of crystallinity.
在所有过渡金属氧化物中，二氧化钛（TiO₂）因其在非晶态和晶态形式下的广泛应用而成为研究最为深入的材料之一。我们通过室温离子等离子体辅助电子束沉积制备了非晶TiO₂薄膜，并对样品进行了热处理以研究结晶的起始过程。在此，我们详细阐述了结晶的最早阶段及其演变，这是退火温度（在250 - 1000°C范围内）和TiO₂厚度（在5至200 nm之间变化）的函数。我们利用原子力显微镜、扫描电子显微镜、X射线衍射仪和拉曼光谱对生长态和热处理后的样品的结构和形态特性进行了探究。我们观察到随着薄膜厚度的减小，结晶起始温度升高，并且根据薄膜厚度的不同，结晶演变也存在显著差异。此外，我们还展示了所使用的互补技术之间存在强烈的相互作用，表明表面成像也可以提供有关材料结晶的独特信息。最后，我们还探究了声子寿命作为TiO₂厚度和退火温度的函数，这两者最终都会影响结晶度。
