Influence of film thickness, substrate temperature and nano-structural changes on the optical properties of UHV deposited Ti thin films

Abstract

Titanium films of different thicknesses ranging from 18 to 210 nm were deposited on glass substrates, at different substrate temperatures (313 to 600 K) under UHV conditions. Their optical properties were measured by spectrophotometry in the spectral range of 200–2500 nm. The optical functions were obtained from the Kramers–Kronig analysis of the reflectivity curves. The effective medium approximation (EMA) analysis was employed to establish the relationship between the structure zone model (SZM) and EMA predictions. There was good agreement between SZM as a function of substrate temperature and film thickness and the values of volume fraction of voids was obtained from EMA analysis. The gettering property of Ti can play an important role in the nano-structure of the film and causes variations in the optical behaviour of thin Ti films, though films were produced under UHV condition and the XRD analysis did not show a detectable amount of oxidation. The over-layer thickness was calculated to be less than 2.0 nm, using the transfer matrix method.

Anodic formation of highly ordered TiO2 nanotube arrays on conducting glass substrate: Effect of titanium film thickness

“…All the sputtered titanium films were anodized at 1.0 mA/cm 2 using an electrolyte containing 0.5% (wt.) [25][26][27] So, 1.5 lm thick titanium films have a lower denseness and higher roughness and volume of the voids. H 2 O in ethylene glycol.…”

Ti/Au Ultrathin Films For TES Application

“…10. For comparison are also reported the optical constant of Ti films grown in ultra high vacuum (Savaloni) [23] and high vacuum (Johnson) [24]. Thicknesses fit parameters are reported in Table I.…”

Kerr and Faraday effects in borate glasses

“…Its chemical stability results in thin though stable surface oxide films, typically a few nanometres in thickness [5]. The previous studies have indicated that the properties of the titanium films depend on the film thickness, the temperature of substrate [7], and the angle of deposition [8]. Even though titanium thin films are so important in different technologies, their optical properties have only been reported by a few researchers (see the works by Johnson and Christy [9] for the thin samples ~ 30 nm and by Lynch et al [10] for the bulk ones).…”

“…It is known that the ratio of the substrate temperature (T s ) to the melting one (T m ) influences both the growth and structure of the films produced under vacuum conditions. A structural zone model comprising three zones has been suggested by Movchan and Demchishin [11] and refined by Thornton [12], in which an additional zone (a so-called transition zone) appears between the zones I and II [7,13]. Many researchers have shown that the I-to-II zone boundary changes from T s > 0.30T m for thicker films to T s > 0.37T m for thinner ones.…”