The study of the oxidation of thin Ti films by neutron reflectometry

Матвеев, В. А.; Pleshanov, N.K.; Bulkin, A.P.; Syromyatnikov, V.G.

doi:10.1088/1742-6596/340/1/012086

Cited by 13 publications

(11 citation statements)

References 10 publications

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“…This would be because Ti becomes oxidized easily. Ti NPs might turn into TiO 2 NPs immediately after they were taken out of the vacuum chamber and exposed to air [37,38].…”

Section: Capturing Charged Nps During Rf Sputtering With a Ti Targetmentioning

confidence: 99%

Generation of Charged Ti Nanoparticles and Their Deposition Behavior with a Substrate Bias during RF Magnetron Sputtering

2020

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This study is based on the film growth by non-classical crystallization, where charged nanoparticles (NPs) are the building block of film deposition. Extensive studies about the generation of charged NPs and their contribution to film deposition have been made in the chemical vapor deposition (CVD) process. However, only a few studies have been made in the physical vapor deposition (PVD) process. Here, the possibility for Ti films to grow by charged Ti NPs was studied during radio frequency (RF) sputtering using Ti target. After the generation of charged Ti NPs was confirmed, their influence on the film quality was investigated. Charged Ti NPs were captured on amorphous carbon membranes with the electric bias of −70 V, 0 V, +5 V, +15 V and +30 V and examined by transmission electron microscopy (TEM). The number density of the Ti NPs decreased with increasing positive bias, which showed that some of Ti NPs were positively charged and repelled by the positively biased TEM membrane. Ti films were deposited on Si substrates with the bias of −70 V, 0 V and +30 V and analyzed by TEM, field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and X-ray reflectivity (XRR). The film deposited at −70 V had the highest thickness of 180 nm, calculated density of 4.974 g/cm3 and crystallinity, whereas the film deposited at +30 V had the lowest thickness of 92 nm, calculated density of 3.499 g/cm3 and crystallinity. This was attributed to the attraction of positively charged Ti NPs to the substrate at −70 V and to the landing of only small-sized neutral Ti NPs on the substrate at +30 V. These results indicate that the control of charged NPs is necessary to obtain a high quality thin film at room temperature.

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“…This would be because Ti becomes oxidized easily. Ti NPs might turn into TiO 2 NPs immediately after they were taken out of the vacuum chamber and exposed to air [37,38].…”

Section: Capturing Charged Nps During Rf Sputtering With a Ti Targetmentioning

confidence: 99%

Generation of Charged Ti Nanoparticles and Their Deposition Behavior with a Substrate Bias during RF Magnetron Sputtering

2020

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“…In the second case, the as-deposited Ti layer was sustained for one week at ambient air to form a native surface oxide layer. 71,72 STS measurements, conductive AFM and current-voltage spectroscopy were carried out with both samples. The presence of native air-formed titanium oxide at the Ti/ta-C interface leads to:…”

Section: Influence Of Quality Of the Underlying Titanium Layermentioning

confidence: 99%

Ultrathin undoped tetrahedral amorphous carbon films: thickness dependence of the electronic structure and implications for their electrochemical behaviour

Protopopova

Miguel

Gabdullin

et al. 2015

Phys. Chem. Chem. Phys.

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In this paper we show that the electronic properties of ultrathin tetrahedral amorphous carbon (ta-C) films are heavily dependent on their thickness. By using scanning tunnelling spectroscopy, Raman spectroscopy, and conductive atomic force microscopy, it was found that a decrease of ta-C thickness from 30 to 7 nm leads to (i) the narrowing of the band gap; (ii) appearance of shallower monoenergetic traps as well as the increase of their concentration; (iii) the increase of the equilibrium concentration of free charge carriers and their mobility; which were caused by (iv) the increase in the sp(2) fraction. However, beyond a certain ta-C thickness (7 nm) the electronic properties of the studied samples start to deteriorate, which is highly likely related to titanium oxide formation at the Ti/ta-C interface. The same tendency is observed for the sample with beforehand air-formed native titanium oxide at the interface. With respect to the last point, it is suggested that the ta-C layer has no uniform coverage if its thickness is small enough (less than 7 nm). The experimental results were rationalized by detailed atomistic simulations. By using the so-called "Tauc plot" we introduce the possibility of the coexistence of bulk and surface band gaps originating from the large increase in sp(2) bonded carbon atoms in the surface region compared to that in the bulk ta-C. The results from the simulations were found to be consistent with the experimental measurements. The previously stated variation in the electronic properties of the layers as a function of their thickness was also exhibited in the electrochemical properties of the samples. It appears that the thinner ta-C layers had more facile electron transfer kinetics as determined with a ferrocenemethanol (FcMeOH) outer sphere redox system. However, if the ta-C layer thickness was reduced too much, the films were not stable anymore.

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“…In order to prepare samples with native titanium oxide at the Ti/ta-C interface, samples with Ti layers were exposed to ambient air for one week before the ta-C deposition. Formation of native titanium oxide is a process described in the literature [49,50]. The titanium nitride interlayer was deposited by DC-MS using nitrogen atmosphere.…”

Section: Sample Preparationmentioning

confidence: 99%

Ultrathin undoped tetrahedral amorphous carbon films: The role of the underlying titanium layer on the electronic structure

Protopopova

Iyer

Kondrateva

et al. 2015

Diamond and Related Materials

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The study of the oxidation of thin Ti films by neutron reflectometry

Cited by 13 publications

References 10 publications

Generation of Charged Ti Nanoparticles and Their Deposition Behavior with a Substrate Bias during RF Magnetron Sputtering

Generation of Charged Ti Nanoparticles and Their Deposition Behavior with a Substrate Bias during RF Magnetron Sputtering

Ultrathin undoped tetrahedral amorphous carbon films: thickness dependence of the electronic structure and implications for their electrochemical behaviour

Ultrathin undoped tetrahedral amorphous carbon films: The role of the underlying titanium layer on the electronic structure

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