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Metal carbides are good candidates to contact carbon-based semiconductors ͑SiC, diamond, and carbon nanotubes͒. Here, we report on an in situ study of carbide formation during the solid-state reaction between thin Ti or Mo films and C substrates. Titanium carbide ͑TiC͒ was previously reported as a contact material to diamond and carbon nanotubes. However, the present study shows two disadvantages for the solid-state reaction of Ti and C. First, because Ti reacts readily with oxygen, a capping layer should be included to enable carbide formation. Second, the TiC phase can exist over a wide range of composition ͑about 10%, i.e., from Ti 0.5 C 0.5 to Ti 0.6 C 0.4 ͒, leading to significant variations in the properties of the material formed. The study of the Mo-C system suggests that molybdenum carbide ͑Mo 2 C͒ is a promising alternative, since the phase shows a lower resistivity ͑about 45% lower than for TiC͒, the carbide forms below 900°C, and its formation is less sensitive to oxidation as compared with the Ti-C system. The measured resistivity for Mo 2 C is =59 ⍀ cm, and from kinetic studies an activation energy for Mo 2 C formation of E a = 3.15± 0.15 eV was obtained.

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Articles you may be interested inInvestigation of ionized metal flux in enhanced high power impulse magnetron sputtering discharges J. Appl. Phys. 115, 153301 (2014); 10.1063/1.4871635 Current-voltage-time characteristics of the reactive Ar/O2 high power impulse magnetron sputtering dischargeThe negative ion flux during reactive sputtering from planar and rotating cylindrical magnetrons has been studied. Energy resolved mass spectrometry was used to measure the energy and mass distribution of the negative ions. Also the angular distribution of the high energy ions was characterized for planar as well as for rotating cylindrical magnetrons. Besides these measurements, a binary collision Monte Carlo simulation code, SiMTRA, was adapted in order to simulate the energy, mass, and angular distribution of the high energy negative ions. All simulated distributions, for both planar and rotating cylindrical magnetrons, were in excellent correspondence with the experimental observations. Also a model for the amount of high energy negative O − ions was proposed. Indeed, the logarithm of the amount of high energy negative O − ions is shown to be related to the secondary electron emission yield of the oxide target, and these two parameters are known to be related to the work function. The SiMTRA simulations, in combination with knowledge of the work function or secondary electron emission yield of the target, allow modeling the flux of high energy negative ions during reactive magnetron sputtering.

Reactive magnetron sputtering is a widely used deposition technique in different application areas. In this study its use is evaluated for the deposition of metal thin films (Al, Cu and Ti) and oxide thin films (Al2O3, TiOx) on woven and nonwoven substrates. The study shows that good adhesion can only be achieved when the substrate is pre-treated in a glow discharge. The influence of the substrate on the reflectivity of Al and Cu thin films was investigated. For conductive textile applications, the resistivity of metal thin films and TiOx was investigated.

After annealing in a H 2 atmosphere at different temperatures, 100 -oriented n-GaAs substrates were metallized with Au and Ti layers of different thicknesses to form Au/n-GaAs and Ti/n-GaAs Schottky diodes. The Schottky barrier height (SBH) variation and its dependence on subsequent N 2 annealing for these Schottky diodes have been studied by different measurement techniques (I-V, C-V and BEEM) to obtain reliable values. These methods show that pre-metallization annealing leads to a less homogeneous metal semiconductor (MS) interface. In case of thick Au layers the effective barrier height is reduced as soon as the H 2 annealing temperature reaches 300 • C. However, GaAs samples covered with thin Au layers or Ti layers do not exhibit such a barrier height reduction. The lower value in the case of thick Au layers is attributed to H + groups, present at the interface due to the annealing in H 2 atmosphere, forming interfacial dipoles with Au, leading to an inhomogeneous barrier and a decrease of the effective barrier height. It seems that these dipoles disappear again in the case of thin Au layers or are not formed with Ti. Post-metallization N 2 annealing at higher temperatures lowers the barrier height for all samples. The resulting barrier inhomogeneities are explained and analysed using the bond polarization theory of Tung ( 2001

In the present work, reactive magnetron sputtering in DC mode was used to grow complex oxide thin films, starting from two separate pure metal targets. A series of coatings was produced with a stoichiometry of the film ranging from MgO, over MgxAlyOz to Al2O3. The surface energy, crystallinity, hardness, refractive index, and surface roughness were investigated. A relationship between all properties studied and the Mg content of the samples was found. A critical compositional region for the Mg–Al–O system where all properties exhibit a change was noticed.