Phase evolution, morphological, optical and electrical properties of femtosecond pulsed laser deposited TiO2 thin films

Abstract

In this paper, we report anatase and rutile titanium oxide (TiO2) nanoparticulate thin films fabricated on silica and Indium Tin Oxide (ITO) substrates using femtosecond pulsed laser deposition (fs-PLD). Depositions were carried-out at substrate temperatures of 25 °C, 400 °C and 600 °C from anatase and rutile phase target materials. Effect of substrate temperature on the surface morphology, microstructural, optical, and electrical properties of these films were systematically investigated by using various range of measurements such as scanning electron microscopy, (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, Ultraviolet–visible-near infrared (UV–Vis–NIR) spectroscopy, and Hall Effect measurements. It is observed that the TiO2 thin films surface are predominated with nanoparticulates of diameter less 35 nm, which constitute about ~ 70%; while the optical bandgaps and electrical resistivity decrease with increasing substrate temperature. A mixed-phase (anatase/rutile) TiO2 thin film was produced at a substrate temperature of 400 °C when samples are fabricated with anatase and rutile target materials. The results of this study indicate that the structural and crystallinity, optical, and electrical properties can be controlled by varying fs-PLD process parameters to prepare TiO2 thin films, which are suitable for applications in photovoltaics, solar cells, and photo-catalysis.

Ultraviolet and visible reflective TiO2/SiO2 thin films on silicon using sol-gel spin coater

“…The vibrational bands of anatase TiO 2 material has centered at 137, 207, 414, 519 and 644.8 cm −1 , respectively, corresponding to the Raman active modes of Eg, Bg, B1g, A1g, and Eg as showed in inserted Fig. 5 [26,27]. It can be concluded that strong anatase peak at 137 cm −1 .…”

The Anodization of Thin Titania Layers as a Facile Process towards Semitransparent and Ordered Electrode Material

“…Various coating methods have been investigated in the literature, for the deposition of Ti and Ti:X (X = heteroatom other than Ti) thin films onto ITO and FTO. Among them, satisfied adhesion of the Ti or Ti:X layer to the substrate has been reported using physical deposition techniques including radio-frequency (RF), pulsed direct current (DC) sputtering, and pulsed laser deposition (PLD) by adjusting the substrate’s temperature in the range of 400–500 °C [ 27 , 28 , 29 ].…”

“…Pulsed laser deposition is a technique that has been also widely utilized for preparing Ti:X layers onto indium tin oxide [ 29 , 36 ]. The morphological features and the electrical properties of Ti:X film deposited onto the TCO can be controlled by varying substrate temperature.…”

“…The morphological features and the electrical properties of Ti:X film deposited onto the TCO can be controlled by varying substrate temperature. Kumi et al [ 29 ] reported that an increase of the substrate temperature to 500 °C leads to an increase in clusters and aggregation of the nanoparticles, which is beneficial to achieve a film with high density and better adhesion. Figure 4 presents the surface morphology the deposited films achive by Kumi et al [ 29 ].…”

“… Surface morphologies of TiO 2 thin flms deposited onto glass substrate by fs-PLD at various substrate temperatures: ( a ) [A1 (25 °C)], ( b ) [A3 (700 °C)] and rutile thin flms: ( c ) [R1 (25 °C)] ( d ) [R3 (700 °C)]. Reprinted from reference [ 29 ] under license CC BY. …”