Reactive Deposition Method Research Articles

イオンビームアシスト蒸着法を用いた酸化チタン薄膜へのクロム添加による光触媒特性への影響

The photocatalytic properties of Cr-doped TiO2 films was investigated by the immersion test in a methylene blue solution under UV light irradiation. The Cr/TiO2 films were prepared as follows; after TiO2 film was prepared on a slide glass substrate by He+-ion beam assisted reactive deposition method (He+-IBARD), Cr was doped into TiO2 films by Ar+-ion beam assisted deposition method (Ar+-IBAD).In the Ar+-IBAD method, Ar+ ion irradiation was carried out during Cr evaporation in order to form the mixing layer of Cr and TiO2. Ar+ ions played an important role to knock on Cr atoms into TiO2 film. The rate of absorbance change for blank of Cr/TiO2 film showed higher value than that of TiO2 film under UV light irradiation. In order to improve photocatalytic properties of Cr-doped TiO2 films, it was required that doped-Cr showed the metal state and amorphous structure.

Ｏ２ビームを利用した反応性蒸着法によるＣｏ‐Ｐｄ‐Ｍｎ‐Ｏ軟磁性膜の作製と磁気特性

Co-Pd-Mn-O granular soft magnetic films with high electrical resistivity were successfully prepared by the reactive deposition method using an O2 molecular beam followed by magnetic field annealing. The films with good soft magnetic properties show Hc of ∼0.3 Oe, 4πMs of ∼7400 G, a uniaxial anisotropy field of ∼120 Oe, and resistivity of ∼200 μΩcm. Such films were found to be composed of oxides of Mn and fcc Co-Pd granules with a particle size of ∼1.5 nm.

Epitaxial growth of titanium oxide thin films on MgO(100) single-crystal substrates by reactive deposition methods

We synthesized titanium oxide thin films on MgO(100) single-crystal substrates by two reactive deposition methods and compared the structures of the thin films formed by these methods. In one method (pulsed-molecular-beam deposition method), molecular oxygen is supplied to the substrates by using a pulsed-molecular-oxygen beam source and deposition of one unit layer of titanium and subsequent supply of molecular oxygen are repeatedly performed. In the other method (radical beam deposition method), atomic oxygen is irradiated to the substrates by using an atomic oxygen beam generated by the radical beam source and irradiation of the atomic oxygen and deposition of titanium are simultaneously performed. In the case of the pulsed-molecular-beam deposition method, the crystal structure was changed by increasing the number of oxygen pulses supplied from the beam source. We found that the crystal structure of titanium oxide depended on the composition ratio of O:Ti in the film. The maximum ratio of O:Ti attainable by this method was 1.85, and at this ratio, (100)-oriented pseudorutile was formed. In the case of the radical beam deposition method, (100)-oriented anatase was formed below the titanium deposition rate of 0.10 nm/s and pseudorutile (TiO 2− δ ) was formed above 0.15 nm/s. The pseudorutile structure synthesized on this experiment was very stable in air. We concluded that the crystal structure of the pseudorutile is a new crystal structure of titanium oxide.

Surface morphology of TiO x films prepared by an ion-beam-assisted reactive deposition method

Surface morphologies of TiO x , films deposited on 304L-SS substrate by an Ar +-ion-beam-assistcd reactive deposition (Ar +-IBARD) method were investigated with respect to the Ar +-ion-current density and thr substrate species, in order to clarify the uiects of Ar +-ion bombardment on film growth. The TiO x film obtained at an ion-current density of 5 μA cm −2 was polycrystalline (rutile-type) with a smooth surface and a uniform cross-sectional structure. The films obtained at higher ion-current densities (15 and 30 μA cm −2) were also polycrystalline (rutile-type) but showed a rough surface with a columnar cross-sectional structure. Film generated without Ar +-ion bombardment was amorphous with relatively uniform cross-sectional structure. No significant differences were observed, however, between the surface morphologies of the TiO x , films on 6 substrates of (304L-SS, Si(100), SnO 2, MgO(100), quartz, glass and titanium). Therefore, a higher flux of Ar +-ion bombardment accelerates crystallization processes.

Ar+イオンアシスト反応性蒸着法により作製されたルチル型TiOx薄膜の電気的特性

Ar⁺イオンアシスト反応性蒸着法により作製されたルチル型TiO_x薄膜の電気的特性

Photocurrent performance of TiOx films prepared by Ar+ ion beam-assisted reactive deposition method

Photocurrent performance and crystalline structures of TiOx films prepared by an Ar+ ion beam-assisted reactive deposition method were investigated. In this method Ar+ ion beam bombardment was carried out at 10 keV simultaneously during Ti evaporation in an oxygen atmosphere. The TiOx films obtained at an ion current density of 10–40 μA cm−2 showed a rutile-type crystalline structure, while the TiOx films obtained at an ion current density below 5 μA cm−2 showed a poor crystallized or amorphous structure. The latter TiOx films were photocatalytically inactive under 196.6 W cm−2 Hg lamp illumination in a solution of 0.1 mol l−1 KHCO3. The maximum photocurrent density of 2.3 mA cm−2 was obtained for the former TiOx films at an electrode potential of 1.5 V. However, this value was much less than that reported for the TiO2 films prepared by a sol-gel method (10 mA cm−2) having an anatase structure. Therefore, the photocurrent performance of TiOx films depends primarily on the crystalline structure.

Direct observation of rare-earth silicide epilayer formation by RHEED technique

The solid phase reaction of yttrium thin film and silicon substrate was investigated in situ with help of RHEED technique. For the first time, we have measured directly yttrium silicide formation temperature which can be as low as 120 °C for a thin (60 Å) metal layer deposited on a Si(111) substrate. For this purpose, we developed a new experimental technique. A study of the growth of thin (10–150 Å) silicon overlayers on yttrium and dysprosium silicide films epitaxially grown on Si(111) was also made. In this paper, an in situ reflection high energy electron diffraction (RHEED) pattern and also azimuthal plot investigation of Si/RE-silicide/Si double heterostructures grown by solid phase epitaxy and reactive deposition method are presented.

Ｆｅ４Ｎ／Ｆｅ多層膜の構造と磁気特性

Magnetic properties of iron nitride thin films as well as Fe4N/Fe multilayered films prepared by a reactive plasma deposition method have been investigated. The Fe4N single phase was produced under PN2=4mTorr, substrate temperature=above 300°C and output power of r.f. generator=above 300W.The multilayered films consisting of Fe/Fe4N/Fe as well as Fe4N/Fe/Fe4N were deposited by control-ling the plasma power. The saturation magnetization of the multilayered films mainly depended on the thickness of the Fe layers. The coercive force of the films was greater than that of the Fe single phase because of nitrogen from the Fe4N layer was diffused into the Fe layer. The film, of a small coercive force of 29 Oe, containing little nitrogen in the Fe layer was made when the deposition rate of the iron in the Fe4N/Fe/Fe4N multilayered film became speeded up.

Structural and superconducting properties of artificially superstructured MoN-TiN films

Superconducting artificially superstructured films (ASFs) composed of MoN and TiN have been prepared by an alternate reactive deposition method. Alternate layers of MoN and TiN were epitaxially grown on MgO(100) single-crystal substrates. Those ASFs with the periodicities of [MoN(0.4 nm)/TiN(0.4nm)], [MoN(0.2 nm)/TiN(3.4 nm)], and [MoN(2.4 nm)/TiN(0.2 nm)] were successfully synthesized. It was confirmed that the precise thickness of ASFs could be controlled on the atomic level. Average lattice constants of ASFs were calculated from the positions of satellite peaks observed in x-ray diffraction. Structural analyses indicate the formation of a single B1-MoN phase when conditions are optimized. ASFs containing B1-MoN layers showed lower superconducting transition temperatures (Tc ’s) than those of ASFs with γ-Mo2N. A few probable reasons for the lower Tc are discussed.

AlN thin films with controlled crystallographic orientations and their microstructure

C-axis oriented AlN thin films, or AlN 〈001〉, are normally obtained by various reactive deposition methods. We have found the AlN thin films with orientations other than 〈001〉 can be prepared by controlling rf sputter deposition conditions. Three different orientations, 〈001〉, 〈102〉, and 〈101〉, were independently grown and verified by x-ray diffraction. A factor controlling the growth habit is discussed. A cross-sectional transmission electron microscopy/scanning transmission electron microscopy technique with microdiffraction was used to study microstructure of the film. It is found that the AlN thin film is grown in a columnar structure and individual columnar grains were verified to be single crystalline.

Problems in the physical vapour deposition of titanium nitride

Abstract Within all currently available reactive physical vapour deposition (PVD) methods for titanium nitride deposition certain difficulties exist which are being overcome to make these processes more viable. The main problems relate to variability, particularly in thickness and phase uniformity, in crystal structure and texture as well as in adhesion. Operators must devote greater attention to these variables which are influenced to some extent by the type of PVD technique adopted. It is also clear that engineers and designers should be more aware of the limitations of each process. The problems specific to the main methods are outlined and information is provided to enable users to appreciate the capabilities of these new techniques.