Here, we report the composite effect of aluminum doping on the dielectric response of Diamond-Like Carbon (DLC) thin films. In addition, the contribution from preparation parameters like acetylene flow rate is also considered to understand sample behavior. AC conductivity study shows the existence of a nonlinear increase of conductivity with frequency leading toward the Jump Relaxation Model (JRM). The transition frequency (ft) is observed, which increases with conductivity. The study reveals that dielectric response is influenced by space charge conductivity, prompting us to adopt the modified Debye law. Deviation from ideal Debye behavior is also confirmed in dielectric modulus analysis. The deviation is frequency-dependent, and a higher deviation is observed in the high-frequency region. Plotting of the Master curve shows the presence of different relaxation dynamics in different samples. A current-voltage (I-V) study of different samples is also undertaken, showing higher values (greater than unity) of the ideality factor.

Herein we have reported the effect of molybdenum (Mo) doping and acetylene (C2H2) gas flow rate, during deposition, on the electrical properties of diamond like carbon (DLC) films. The frequency dependent dielectric response of the undoped and doped DLC films has been discussed in details. Mo doping also increases the dielectric constant value owing to interfacial polarization and the corresponding change with C2H2 gas flow rate has been attributed to the formation of sp2 bonding over sp3 bonding, favoring the emergence of a graphite-like phase. The ac conductivity of DLC films has been observed to increase with frequency following a power law behavior. However, with 29 % Mo doping we have noticed two plateau regions having different slopes which has been explained on the basis of the jump relaxation model (JRM). The theoretical fitting of the experimental data indicates occurrence of ionic conduction along with polaron hoping. The dc contribution part (odc) of the measured ac conductivity is found to vary with the acetylene (C2H2) gas flow dependent sp2 bonding formation. The odc is extracted to be 2351 S/m for the 29 % Mo doped DLC films. From the Nyquist plot in impedance spectroscopy single relaxation phenomena have been observed for the no or low Mo doping but with 29 % Mo doping both the grain and grain boundary effect are prominent. This also suggests the presence of sp2 hybrid-ization and formation of dangling bonds between the metal carbide and DLC film. From the current voltage characteristics, the development of high sp2 bonding and high electron injection into the DLC matrix with subsequent change in nature of the DLC from semiconducting to metallic with high Mo doping has been reported. From the capacitance voltage characteristics study it has been found that either increase in acetylene gas flow during deposition or Mo doping increases the space charge and trap carrier densities.

Plasma source ion implantation (PSII) is a technique that is suitable for implantation as well as film deposition. Since it involves a high voltage that is applied to the sample holder to attract ions from the plasma to the sample, an influence can be expected in case that either the whole substrate or a part of it is nonconductive. Diamond-like carbon (DLC) films were deposited by PSII, using C2H2 as precursor. The substrates were silicon samples that were placed on a large, horizontally oriented conductive sample holder in three different ways: 1) directly on the holder, 2) with an alumina block of 5 mm height between holder and sample, and 3) with an alumina block of 12 mm height between holder and sample. A high voltage (pulse or DC) was applied directly to the sample holder. The plasma was generated by this voltage or, in some experiments, by an additional RF signal, which was applied to a plate that was oriented parallel to the sample holder in a distance of 100 mm. The investigation of the effect of the presence of the insulating alumina block on the film properties focused on the deposition rate, the hydrogen content and film structure, the surface roughness, the hardness and the friction coefficient of the films.

The dielectric constant, impedance spectroscopy, ac conductivity, and dc conductivity of Ni-doped diamond-like carbon (DLC) films are reported within a wide temperature and frequency window. The dc conductivity increases with temperature, possessing different activation regions. At higher temperatures, a reversible semiconductor to metal transition is observed in the doped samples. Both the ac and dc conductivities are observed to increase with Ni doping concentration. However, the dc self-bias plays an important role in conductivity. The ac conductivity follows Jonscher's power law. The frequency exponent study shows that the ac conduction is governed by the correlated barrier hopping model. The grain boundary resistance is found to be higher than the grain resistance. According to the electric modulus study, the undoped DLC deviates from the ideal Debye behavior, with the deviation being higher in the high-frequency region. The current-voltage characteristics show a nonlinear hysteresis behavior.

We report on the dielectric constant, conductivity, impedance spectroscopy and current-voltage characteristic of zinc contain diamond-like carbon (Zn-DLC) films prepared by a combination of plasma source ion implantation with magnetron sputtering of a zinc target. The frequency variation of the AC conductivity follows Jonscher's power law. The temperature variation of the frequency exponent indicates that the charge carriers follow a correlated barrier hopping conduction mechanism. The frequency dispersion of real and imaginary part of the dielectric constant obeys a modified Cole-Cole equation. The space charge conductivity, free charge conductivity and relaxation time of the Zn-DLC thin films are temperature dependent. The relaxation time decreases with increase in temperature. The Nyquist plot of complex impedance spectroscopy is simulated by a simple electrical equivalent circuit. The imaginary part of the complex impedance shows a relaxation peak, which shifts towards the high frequency side with an increase in temperature. The temperature dependent current-voltage (I-V) characteristic shows a non-linear type behaviour which follows the Poole-Frenkel (PF) emission model. To investigate the photosensitivity of an Ag/Zn-DLC/Si device, we placed it in dark and UV light condition and measured the (I-V) characteristic at room temperature. The dark current density and photocurrent density follow the PF model and a modified PF model respectively.

Iodine containing diamond-like carbon (DLC) films were prepared by a plasma-enhanced chemical vapor deposition process using a mixture of trifluoroiodomethane (CF3I) and acetylene (C2H2) as plasma gas. The resulting films contain iodine throughout but are mostly fluorine free. Even though the precursor contains more fluorine than iodine, fluorine is only present in larger concentrations in the surface and interface region. The films are smooth, show a decreased hardness and a higher contact angle as compared to iodine free DLC films. (C) 2017 Elsevier B.V. All rights reserved.

The addition of halogens to diamond-like carbon (DLC) films provides attractive film properties, e.g. a hydrophobic surface combined with an improved corrosion protection. The use of iodine is of interest in this regard because of its additional marked influence on the band gap and therefore on the optical properties of the film. Instead of solid iodine, the gaseous precursor trifluoroiodomethane (CF3I) was used to prepare iodine containing DLC films. In contrast to our earlier experiments, a lower voltage was used in the plasma based preparation process thereby extending the iodine concentration range. The film properties, such as halogen content, bonding, water contact angle and corrosion protection were evaluated. The iodine containing DLC films are suitable to be deposited on polymer materials.

Carbon can play a decisive role in the preparation of the titanium dioxide modification anatase. Amorphous titanium containing diamond-like carbon films are a suitable basis for this process. Those films can be deposited by a process that combines reactive magnetron sputtering with plasma source ion implantation, using a mixture of argon and ethylene (C2H4) for the plasma. After film deposition, annealing of the samples for 1 h at a fixed temperature between 723 K and 873 K in ambient atmosphere led to oxidation and crystallization. Colorless pure anatase was observed after annealing. (C) 2017 Elsevier B.V. All rights reserved.

Copper is one of the substrates that are difficult to coat with a diamond-like carbon film because of the latter's poor adhesion. Two factors that can improve the adhesion in this case are the surface roughness and the oxidation of the surface. The dependence of the adhesive strength of the diamond-like carbon film on both factors was measured for samples that were prepared by a plasma process using a pulsed voltage. The main parameter was the ion energy of the oxygen ions. For pulse voltages higher than −16kV a drastically increased adhesion was found, correlated to a rough surface and the presence of Cu2O in the interface. The adhesive strength of the film surpasses the maximum amount that can be measured with a pull test. The same good adhesion can be realized at lower voltages by changing the plasma gas to a mixture of oxygen and argon. The additional argon changes the surface topography of a polycrystalline copper substrate.

A sample holder with a large open area offers several benefits when used in the process of plasma immersion ion implantation and deposition in which the plasma is generated by a high voltage applied to the sample holder: The ignition voltage of the plasma is lower, and the deposition rate can be several times higher than in the case of a normal plate-like holder. There is a more pronounced edge effect regarding the film thickness. Other film properties are also affected; for diamond-like carbon films, the film structure exhibits more disorder. The hardness of the samples is similar, with the surfaces of the samples being very smooth.

The long-term stability of silicon-containing diamond-like carbon films was investigated. The samples were prepared by plasma source ion implantation with a mixture of tetramethylsilane (TMS) and acetylene (C2H2) using negative high voltage pulses. The film composition was changed by varying the flow rates of the TMS and C2H2 gases, resulting in a Si content from 0 to 44at.%. After deposition the films were annealed at temperatures from 523K to 773K for 168h in ambient air. The effect of the Si content on the structure, the mechanical and tribological properties of the DLC films was investigated. A silicon oxide layer is produced on the surface of the film which improves the thermal stability. Mechanical and friction characteristics of the Si-DLC were not much affected by the long-term thermal annealing if the temperature was kept below 573K.

The conversion of the surface layer of a titanium containing sample into anatase has been tried many times by oxygen implantation and simultaneous or subsequent heating. The result, however, was in most cases the titanium dioxide modification rutile or, especially for titanium alloys, a mixture of anatase and rutile. Here a method is presented to manufacture a titanium dioxide surface layer with an initial implantation of carbon into the surface. A subsequent heating in air removes most of the carbon and replaces it with oxygen, thus generating the anatase modification.

The addition of nitrogen to diamond-like carbon films affects properties such as the inner stress of the film, the conductivity, biocompatibility and wettability. The nitrogen content is limited, though, and the maximum concentration depends on the preparation method. Here, plasma immersion ion implantation was used for the deposition of the films, without the use of a separate plasma source, i.e. the plasma was generated by a high voltage applied to the samples. The plasma gas consisted of a mixture of C2H4 and N-2, the substrates were silicon and glass. By changing the experimental parameters (high voltage, pulse length and repetition rate and gas flow ratio) layers with different N content were prepared. Additionally, some samples were prepared using a DC voltage. The nitrogen content and bonding was investigated with SIMS, AES, XPS, FTIR and Raman spectroscopy. Their influence on the electrical resistivity of the films was investigated. Depending on the preparation conditions different nitrogen contents were realized with maximum contents around 11 at.%. Those values were compared with the nitrogen concentration that can be achieved by implantation of nitrogen into a DLC film. (C) 2015 Elsevier B.V. All rights reserved.

A method is presented which leads to a higher sputter rate as compared to the sputtering of the surface of a bulk sample under the same sputtering conditions: the target is coated beforehand by a separate process to produce a nanostructured film on its surface. In the case of silver, the sputter yield under ion bombardment is 1.7 times higher. If the ions for the bombardment are generated by a voltage applied to the sample, then improvements up to a factor of five can be realized.

Adhesive diamond-like carbon (DLC) films can be prepared by plasma source ion implantation (PSII), which is also suitable for the treatment of the inner surface of a tube. Incorporation of a metal into the DLC film provides a possibility to change the characteristics of the DLC film. One source for the metal is DC sputtering. In this study PSII and DC sputtering were combined to prepare DLC films containing low concentrations of Ag on the interior surfaces of stainless steel tubes. A DLC film was deposited using a C2H4 plasma with the help of an auxiliary electrode inside of the tube. This electrode was then used as a target for the DC sputtering. A mixture of the gases Ar and C2H4 was used to sputter the silver. By changing the gas flow ratios and process time, the resulting Ag content of the films could be varied. Sample characterizations were performed by X-ray photoelectron spectroscopy, secondary ion mass spectrometry, atomic force microscopy and Raman spectroscopy. Additionally, a ball-on-disk test was performed to investigate the tribological properties of the films. The antibacterial activity was determined using Staphylococcus aureus bacteria. (C) 2014 Elsevier B.V. All rights reserved.

The authors regret that in Table 2 the values for thewater contact angles of sample #1were reported incorrectly. In the values for both substrates the 1 has to be replaced by an 8, i.e. 89.0 instead of 19.0 and 80.6 instead of 10.6. The corrected table is reproduced below. The authors regret that this error in transcription has not been spotted earlier in the publication process. The authors would like to apologise for any inconvenience caused.

The adhesion of diamond-like carbon (DLC) films on copper substrates is usually very poor. However, the adhesive strength of the films can be improved by a preimplantation step. With plasma based ion implantation and deposition, the preimplantation step and the film deposition can be realized with the same experimental setup. The effect of the implantation of several different gaseous species (N-2,O-2, Ar, CO2, C2H4, and air) at 10 kV was investigated. For O-2, N-2 and C2H4 the influence of the pulse voltage (-5, -10, -15 kV) was examined. The samples were characterized by elemental depth profiling (XPS, SIMS), and the adhesion was evaluated with a pull tester.Most of the preimplantation treatments increase the adhesion of the DLC films on the copper substrates considerably to values of 10-15 MPa. The best result was obtained with -15 kV oxygen preimplantation. (C) 2013 Elsevier B.V. All rights reserved.

Ag-containing diamond-like carbon (DLC) films were prepared on austenitic type stainless steel SUS316L and silicon wafer substrates by a process combining reactive magnetron sputtering with plasma source ion implantation (PSII). An Ag disc was used as a target for the sputter source with an RF power of 100 W. A mixture of the gases Ar and C2H2 was introduced into the discharge chamber while a negative high voltage pulse was applied to the substrate holder. By changing the gas flow ratios the resulting Ag content of the films could be varied. The prepared films were composed of amorphous carbon with crystalline Ag, as observed by X-ray diffractometry and TEM. Additional sample characterizations were performed by X-ray photoelectron spectroscopy, secondary ion mass spectrometry and Raman spectroscopy. The surface morphology was observed by scanning electron microscopy. The antibacterial activity was determined using Staphylococcus aureus bacteria. All Ag-containing diamond-like carbon films exhibited an antibacterial activity with only small variations depending on the Ag content. (C) 2012 Elsevier Ltd. All rights reserved.

The aim of this investigation was to find a suitable pretreatment for the subsequent deposition of DLC films on a steel substrate. The implantation should on the one hand improve the corrosion properties of the steel substrate and on the other hand increase the adhesion of the DLC film to the substrate. Three different gases (oxygen, nitrogen, ethylene) were used for the implantation (voltage pulses of -10 kV), and the deposition (-15 kV) was performed with C2H4 on stainless steel substrates and silicon wafer by plasma based ion implantation and deposition (PBII&D).The influence of the different implantation gases on the composition, structure and corrosion resistance of the surface was studied. The surface morphology was changed depending on the working gas. In all implantation samples a composition gradient layer in the surface was confirmed by measurement of the depth distribution by SIMS and XPS. The DLC films as prepared with C2H4 PBII&D exhibited roughness, hardness, and friction properties similar to those of DLC films prepared by other hydrocarbon gases. The corrosion protection potential in an aqueous environment was evaluated by cyclic voltammetiy. The oxygen and nitrogen implantations improved the corrosion protection properties. These two pretreatments also exhibited a good corrosion protection in combination with the DLC film coatings. This is due to the resulting bonding states in the implanted surface and due to an increased adhesion of the DLC films to the substrates as could be seen after the corrosion tests. (C) 2013 Elsevier B.V. All rights reserved.