No abstract

No abstract

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.

No abstract

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.