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The Ni-Ti system is the most popular of the SMA’s because of its large recovery force, a transformation temperature near room temperature and a good oxidation resistance. Although the transformation frequency is low (mainly limited by thermal inertia), a thin film of Ni-Ti coupled with silicon for heat dissipation can produce cycling frequencies much larger than the typical macrosize structures. The thin films can be electrically driven using joule heating, and they demonstrate fast cooling rates because of their large surface-to-volume ratio. The control of film composition and properties has proven difficult in sputter-deposited films, and a deeper study of deposition techniques is needed. Furthermore, the as-deposited films show an amorphous structure and thus have to be heat treated to induce crystallization in order to have the shape memory effect. In the present study, thin films have been prepared by dc and rf magnetron sputtering. The crystallization of these films has been studied by in-situ grazing incidence X-Ray diffraction (GIXRD), allowing us to establish a correlation between the deposition conditions and the tendency for crystallization.

The Ni-Ti system is the most popular of the SMA’s because of its large recovery force, a transformation temperature near room temperature and a good oxidation resistance. Although the transformation frequency is low (mainly limited by thermal inertia), a thin film of Ni-Ti coupled with silicon for heat dissipation can produce cycling frequencies much larger than the typical macrosize structures. The thin films can be electrically driven using joule heating, and they demonstrate fast cooling rates because of their large surface-to-volume ratio. The control of film composition and properties has proven difficult in sputter-deposited films, and a deeper study of deposition techniques is needed. Furthermore, the as-deposited films show an amorphous structure and thus have to be heat treated to induce crystallization in order to have the shape memory effect. In the present study, thin films have been prepared by dc and rf magnetron sputtering. The crystallization of these films has been studied by in-situ grazing incidence X-Ray diffraction (GIXRD), allowing us to establish a correlation between the deposition conditions and the tendency for crystallization.

The Ni-Ti system is the most popular of the SMA’s because of its large recovery force, a transformation temperature near room temperature and a good oxidation resistance. Although the transformation frequency is low (mainly limited by thermal inertia), a thin film of Ni-Ti coupled with silicon for heat dissipation can produce cycling frequencies much larger than the typical macrosize structures. The thin films can be electrically driven using joule heating, and they demonstrate fast cooling rates because of their large surface-to-volume ratio. The control of film composition and properties has proven difficult in sputter-deposited films, and a deeper study of deposition techniques is needed. Furthermore, the as-deposited films show an amorphous structure and thus have to be heat treated to induce crystallization in order to have the shape memory effect. In the present study, thin films have been prepared by dc and rf magnetron sputtering. The crystallization of these films has been studied by in-situ grazing incidence X-Ray diffraction (GIXRD), allowing us to establish a correlation between the deposition conditions and the tendency for crystallization.

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We report on the microstructure, morphology, and growth of 5,5′-bis(naphth-2-yl)-2,2′-bithiophene (NaT2) thin films deposited on graphene, characterized by grazing incidence X-ray diffraction (GIXRD) and complemented by atomic force microscopy (AFM) measurements. NaT2 is deposited on two types of graphene surfaces: custom-made samples where chemical vapor deposition (CVD)-grown graphene layers are transferred onto a Si/SiO2 substrate by us and common commercially transferred CVD graphene on Si/SiO2. Pristine Si/SiO2 substrates are used as a reference. The NaT2 crystal structure and orientation depend strongly on the underlying surface, with the molecules predominantly lying down on the graphene surface (face-on orientation) and standing nearly out-of-plane (edge-on orientation) on the Si/SiO2 reference surface. Post growth GIXRD and AFM measurements reveal that the crystalline structure and grain morphology differ depending on whether there is polymer residue left on the graphene surface. In situ GIXRD measurements show that the thickness dependence of the intensity of the (111) reflection from the crystalline edge-on phase does not intersect zero at the beginning of the deposition process, suggesting that an initial wetting layer, corresponding to 1-2 molecular layers, is formed at the surface-film interface. By contrast, the (111) reflection intensity from the crystalline face-on phase grows at a constant rate as a function of film thickness during the entire deposition.