Direct Ion Beam Deposition Method Research Articles

Oxygen doping effect on wettability of diamond-like carbon films

DLC films were deposited on Ge substrates using direct ion beam deposition method, followed by investigating the influence of O2 doping on their morphological, electrical, and structural properties. The films were doped with oxygen under flow rates of 5, 10, 20, and 40 sccm (standard cubic centimeters per minute). The structure of the films was studied by Raman spectroscopy. Result showed that by increasing oxygen incorporation, sp2 content decreases, sp3 content increases, and the C-C bonding loses its order. The hydrophilicity of the layers was analyzed by the contact angle measuring experiment. The results showed that by increasing the O2 flow ratio from 5 to 40 sccm, the percentage of O2 increases from 1.1 to 3.9%. The water contact angle measurement showed that an increase in oxygen flow ratio results in a decrease in contact angle from 82.9° ± 2.1° to 50° ± 3°.

Changes in Amorphous Hydrogenated Carbon Films by Ultraviolet and Infrared Laser Irradiation

Amorphous hydrogenated carbon lms were formed on the Si (100) wafers by a direct-ion beam deposition method from pure acetylene and acetylene hydrogen gas mixtures. The lms were irradiated with a nanosecond Nd:YAG laser working at the rst harmonics (λ1 = 1064 nm), the fourth harmonics (λ4 = 266 nm) or with a Nd:YVO4 laser working at the third harmonic (λ3 = 355 nm). The lms were studied by the Raman scattering, micro-Fourier transform infrared and Fourier transform infrared spectroscopies, null-ellipsometry, optical and scanning electron microscope, and Vickers hardness method. Irradiation by the wavelength λ1 = 1064 nm leads to graphitization and formation of the silicon carbide, because of the silicon substrate decomposition. The samples were strongly modi ed after the irradiation by λ3 = 355 nm the thickness of the lms decreased, and silicon carbide was formed. It was observed that nano-structured materials (e.g. carbon nano-onions, nc-diamond) were formed after the irradiation by λ4 = 266 nm.

Optical properties of diamond‐like carbon films irradiated by X‐ray photons

AbstractAmorphous diamond like carbon (DLC) films deposited at room temperature on quartz glass wafer by means of direct ion beam deposition method from acetylene gas or hexamethyldisiloxane (HMDSO) vapour mixture with hydrogen and nitrogen gas were irradiated by high energy X‐ray photon and the optical properties of irradiated DLC films were investigated. Ionizing radiation induced modification of optical properties of the DLC films of different type were studied using UV–VIS spectrometry, laser ellipsometry, Raman and IR spectroscopy, and interpreted on the basis of the obtained results. It was found, that the irradiation of amorphous hydrogenated DLC films introduced significant changes in the investigated structures; however the properties of SiOx containing DLC films remained almost stable after their exposure with high energy X‐ray photons. The influence of film deposition conditions and co‐doping on the optical properties of irradiated DLC films and the role of hydrogen in the films are discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Radiation induced changes in amorphous hydrogenated DLC films

Amorphous hydrogenated diamond-like carbon (DLC) films synthesized at room temperature from acetylene gas on quartz glass wafers by means of the direct ion beam deposition method and irradiated with X-ray photons of different energy were investigated. Ionizing radiation induced changes of bonding structure in a-C:H films of different thickness and different density were studied using Raman and infrared spectroscopy and atomic force microscopy. Optical transmittance spectra of the DLC films in UV–vis range were measured as well. The influence of technological deposition characteristics on the optical properties of irradiated amorphous DLC films and the role of the hydrogen in the DLC films were estimated and discussed with the purpose to assess possible application of amorphous hydrogenated DLC films as the protective coatings in radiation detectors. All investigated DLC films showed some increasing tendency of the optical transmittance in the visible and infrared range after the irradiation. Low density PLCH films irradiated with high energy X-ray photons were highly transparent in the whole UV–vis range and indicated possible changes in the bonding structure of the irradiated samples, which have been discussed on the basis of the results obtained during this investigation.

Electrical properties of the diamond like carbon films irradiated with high energy photons

SiOx—containing amorphous diamond like carbon (DLC) is very attractive material for a number of practical applications. DLC films are possible candidates for the formation of passive layers in electronic devices and are used as protective coatings. Both applications are interesting for the construction of medical radiation detectors. Radiation induced structural changes and electrical properties of DLC: SiOx films (undoped and co-doped) synthesized at room temperature by means of direct ion beam deposition method were investigated after their irradiation with high energy (Emax = 15 MeV) X-ray photons. It was found that transparency of the irradiated DLC films was not changed significantly, as compared to initial samples, stating only small increase of the optical band gap in DLC films. However radiation induced changes were dependent on co-doping and film deposition conditions which were responsible for the sp3/sp2 ratio and hydrogen content in the investigated films. Analysis of U-I characteristics showed decreasing tendency of the leakage current in the range 0–20 V and especially high dependency of breakdown voltage on the deposited contact area in irradiated films as compared to initial samples. Possible mechanism of radiation induced changes in irradiated DLC films is discussed on the basis of the results of Raman and Infrared spectroscopy.

Hydrogen influence on the structure and properties of amorphous hydrogenated carbon films deposited by direct ion beam

The present work provides results for amorphous hydrogenated carbon (a-C:H) films grown by direct ion beam deposition method. Acetylene and its mixtures with hydrogen were used. The films were characterized by Rutherford backscattering spectrometry, elastic recoil detection, Raman spectroscopy, ellipsometry, infrared spectroscopy, and microhardness measurements. These techniques indicated that an admixture of hydrogen yields a lower deposition rate, a higher content of total and bounded hydrogen in the a-C:H films, and a lower film density. The optical and mechanical properties depend on both, hydrogen concentrations in the gas phase and in the films, and show a strong diamond-like component, which reaches maximum at 34 at.% of hydrogen. Further hydrogen dilution enhanced only sp 2 clustering and possible reduced a number of both sp 3 and C–C sp 3 bonds. We suppose that these effects (in the high hydrogen concentration range) are not only related to the ion irradiation difference between the light hydrogen and the much heavier carbon but also to the diffusion in the a-C:H films.

Modification of amorphous a-C:H films by laser irradiation

Amorphous diamond-like hydrogenated carbon lms a-C:H were formed on Si wafers by a direct ion beam deposition method from acetylene or a gas mixture of acetylene and hydrogen. The samples were irradiated in a scanning mode by second harmonic (wavelength ‚ = 532 nm) of a Q-switched YAG : Nd laser. The effect of laser irradiation was studied by Raman and infrared spectroscopy and spectroscopic ellipsometry. The changes in the optical spectra of the samples with different H amount were investigated in the dependence on laser intensity. Experimental data were interpreted taking into account the structural transformations of a-C:H lms.

Investigation of optical properties of a-C:H films deposited from acetylene using direct ion beam deposition method

The present work provides results for amorphous hydrogenated carbon (a-C:H) films deposited by a direct ion beam deposition method. Acetylene (C 2H 2) precursors and their mixture with hydrogen (H 2) were used. The films were characterized by Raman spectroscopy (RS) and ellipsometry measurements. RS indicates an increase of sp 3/sp 2 bonding ratio and disorder in graphite clusters with increasing hydrogen content (from 0 to 50% for acetylene precursor) in the deposition of gas mixture. The opposite trend is observed when the hydrogen concentration exceeds 50% (for acetylene). The ellipsometric technique was used to reveal the optical constants of a-C:H films from the optical response of the complex system in the UV–VIS–NIR spectral range 0.5–5.0 eV. In the analysis of the optical response, the models of effective film and a multi-layer stack were used for a-C:H films.

The role of hydrogen in a-C:H films deposited from hexane or acetylene using direct ion beam deposition method

The present work provides results of amorphous hydrogenated carbon (a-C:H) films deposited by direct ion beam deposition method. Hexane (C 6H 14+H delivery) or acetylene (C 2H 2) precursors and their mixture with hydrogen (H 2) were used. The films were characterized by Raman spectroscopy (RS), ellipsometry, and electrical resistance measurements. RS indicates increase in sp 3/sp 2 bonding ratio and disorder in graphite clusters, upon increasing of hydrogen content (from 0% to 50% for acetylene precursor) in the deposition gas mixture. The opposite trend is observed when the hydrogen concentration exceeded 50% (for acetylene) or additional hydrogen was added (for hexane). The data of electrical resistance measurements support the correlations defined by RS.

Synthesis of nanocrystalline diamond by the direct ion beam deposition method

Nanocrystalline diamond has been synthesized on a mirror-polished Si(001) substrate by means of direct ion beam deposition. Low-energy (80–200 eV) hydrocarbon and hydrogen ions, generated in a Kaufman ion source, were used to bombard the substrates. The bombarded samples were characterized by high-resolution transmission electron microscopy and Raman spectroscopy. Nanocrystalline diamond particles of random orientation were observed in a matrix of amorphous carbon film on the Si(001) substrate. The size of the nanocrystalline diamond particles varied in the range of 50–300 Å. The mechanism of ion-induced formation of nanocrystalline diamond is discussed.

Precursor gas effect on the mechanical and optical properties of ion beam deposited diamond-like carbon films

The effect of precursor gases on the diamond-like carbon (DLC) film deposition was investigated by the direct ion beam deposition method. DLC films were deposited using methane and benzene as the precursor gases. Ion energies for the deposition range from 100 to 700 eV were achieved by adjusting the beam voltage. The residual stresses, refractive indices and optical band gaps were compared at the same ion energy. We observed significant differences in residual stress and optical properties between these films. As in r.f. plasma-assisted CVD, the residual stresses of the films deposited from benzene show a characteristic behaviour of lower ion energy deposition than those deposited from methane. The present observations are discussed in terms of the difference in ion energy per carbon atom at the growth surface. We also observed that the Ar addition effect on the residual stress is strongly dependent on the precursor gases.

Fabrication of W/C Multilayers by Direct Ion Beam Deposition

ABSTRACTThe multilayer structures of tungsten and carbon for soft x-ray mirrors were fabricated by the low energy (<100eV) direct ion beam deposition method with various depositing ion energies. The layered structures were observed by cross sectional TEM. The undulated structures were found in the layered structures of the depositing ion energy of 6OeV and lOOeV. It becomes larger as the depositing ion energy increases, and the undulation of the upper layers was larger than that of the under layers. The undulation seems to increase in each carbon layer. These results are quite different from the results of evaluation of thick monolayer films in the previous work. Then, the interfacial composite layer was evaluated by XPS. The tungsten carbide layer was found at the W/ C interface on the C layer. However, we can not find such layer at the interface on the W layer. This result can be explained by the difference of the momentum of the depositing ion.