Phase Transitions of Polarised PVDF Films in a Standard Curing Process for Composites

The article reports on the influence of annealing PVDF in an autoclave process on the PVDF phase composition. DSC, FTIR and XRD measurements serve to observe the phase changes in an already stretched, polarised and β-phase rich film. Annealing was conducted between 90 and 185 ∘C to cover a broad range of curing processes in an autoclave. The β-phase is found to be stable up to near the melting range at 170 ∘C. At 175 ∘C, the non-piezoelectric α-phase dominates and the piezoelectric γ- and γ′-phases appear. The γ-phase grows at elevated temperatures and replaces the β-phase. This observation stresses the importance of developing new methods to reactivate the polarisation after annealing, in particular for the integration of PVDF as a sensor in laminated structures, such as CFRP.

Magnetotransport Properties of Semi-Metallic Bismuth Thin Films for Flexible Sensor Applications

In this paper we describe characterization of semi-metallic bismuth thin films. We prepared bismuth thin films by a deposition of bismuth through thermal evaporation onto flexible Kapton substrates and annealing at temperatures close to the melting point of Bi. We studied the morphology and transport properties of these films. Immediately after the deposition we observed competition between vanishing of the grain boundaries and elastic strain energy, which stabilized at larger thicknesses leading to the grain size of 140 nm. This effect was accompanied by a continuous decrease of resistivity which, however, was larger than for the bulk bismuth. The film annealing at temperatures close to the melting point of Bi led to a 300% increase of magnetoresistance at room temperature and in the magnetic field of 7 T. The in situ resistance measurements allowed us to determine the permissible temperature at which the annealing does not cause the loss of film continuity.

A novel process for SiGe Core-Shell JAM Transistors Fabrication and thermal annealing effect on its electrical performance

In this study, we fabricate Si/SiGe core-shell Junctionless accumulation mode (JAM)FinFET devices through a rapid and novel process with four main steps, i.e. e-beam lithography definition, sputter deposition, alloy combination annealing, and chemical solution etching. The height of Si core is 30 nm and the thickness of Si/SiGe core-shell is about 2 nm. After finishing the fabrication of devices, we widely studied the electrical characteristics of poly Si/SiGe core-shell JAM FinFET transistors from a view of different Lg and Wch. A poly-Si/SiGe core -shell JAMFETs was successfully demonstrated and it also exhibits a superior subthreshold swing of 81mV/dec and high on/off ratio > 105 when annealing for 1hr at 600°C. The thermal diffusion process condition for this study are 1hr at 600°C and 6hr at 700°C for comparison. The annealing condition at 700oC for 6 hours shows undesired electrical characteristics against the other. Results suggests that from over thermal budget causes a plenty of Ge to precipitate against to form SiGe thin film. Annealing JAMFETs at low temperature shows outstanding Subthreshold swing and better swing condition when compared to its counterpart i.e. at higher temperature. This new process can still fabricate a comparable performance to classical planar FinFET in driving current.

Oxidation of Thin Titanium Films: Determination of the Chemical Composition of the Oxide and the Oxygen Diffusion Factor

The morphologies and local electronic structures of titanium coatings deposited on the surfaces of highly oriented pyrolytic graphite were determined. Chemical compositions of the oxides formed on the coating surfaces were established. A theoretical model was developed describing the changes in the TiOx oxides (1.75 < x < 2) band gap depending on the duration and temperature of the titanium film annealing procedure in oxygen. The effective activation energy of oxygen diffusion in TiOx (1.75 < x < 2) was determined, and the pre-exponential factor of the diffusion coefficient was estimated.

Preparation of Large-Scale CoS2 Nanowires and their Raman Study

Structurally sound self-growing large-scale CoS2 nanowires were synthesized via a template-free and catalyst thermal sulfurization process on Co films. After annealing cobalt thin films in pure sulfur (S) vapor produced large area of CoS2 nanowires, we observe symmetrical and vertically alligned nanowires on the thin film surface. After running the thermal treatment in static S atmosphere, the cobalt thin film is converted into polycrystalline CoS2 nanowires and CoS2 film. We recorded the form of the CoS2 nanowires after the cobalt thin film was annealed. We also investigated the influence of the film annealing time and temperature. Aligned and long nanowires can be effectively formed at a temperature of around 400 °C for 5-10 h. The diameter of the CoS2 nanowires is around 10 nm with a length of ~ 2 µm. In addition, the Raman spectra of isolated CoS2 nanowired were lso studied.