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However, there have been

However, there have been reports about meta-stability in the system in both concentration- and temperature-driven non equilibrium transitions. For instance, the meta-stable WC1−x and W2C are formed as kinetic products from rapid cooling of WC. Since the sample are created by dual magnetron deposition, a non-equilibrium transitions, WC1−x and W2C can be obtained directly after sputtering or after heat treatment, as result of kinematic hindering [16]. - 22 -

Chapter 3 3.1 Experimental Two different type of substrate materials, both with a dimension: 12x15 mm 2 were used to study the carbide formation of a-C:W films: 1. Polished single crystal Silicon Wafer (100). 2. Pyrolytic graphite cut parallel to basal planes and polished with diamond paste. Both substrates were chosen for the good adhesion of the deposition and little influence during heat treatment. Before deposition, all samples were ultrasonically cleaned in isopropanol for 5 min. After cleaning in bath all samples were washed again with isopropanol, to remove any particle attached to the surface and avoid drying of isopropanol with these particles. After cleaning the samples were placed onto a round sample holder, which could be placed in the sputtering device. The samples are located onto the sample holder as seen in figure 3.1. In the middle of the holder is a unbroken polymer-silicon coated wafer. The samples are placed equally dispersed around the silicon wafer in longitudinal direction, due to the gradient in deposition rate, hence; all samples are the same. The edge of one silicon substrate was covered with a tape to protect it from deposition. The thickness of the films could be measured afterwards with a profilometer after removing the tape. The film material was attained as a powder by inserting the coated wafer into acetone to solve the polymer. The sample holder is placed onto a rotating disk within the sputtering device, guarantying uniform thickness and composition. The chamber was pumped overnight with a turbo 6 molecular vacuum pump to a base pressure of 8.4 10 Pa . - 23 -

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