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This paper reports on the deposition and characterization of piezoelectric AlXSc1-XN (further: AlScN) films on Si substrates using AlSc alloy targets with 30 at.% Sc. Films were deposited on a Ø200 mm area with deposition rates of 200 nm/min using a reactive magnetron sputtering process with a unipolar–bipolar hybrid pulse mode of FEP. The homogeneity of film composition, structural properties and piezoelectric properties were investigated depending on process parameters, especially the pulse mode of powering in unipolar–bipolar hybrid pulse mode operation. Characterization methods include energy-dispersive spectrometry of X-ray (EDS), X-ray diffraction (XRD), piezoresponse force microscopy (PFM) and double-beam laser interferometry (DBLI). The film composition was Al0.695Sc0.295N. The films showed good homogeneity of film structure with full width at half maximum (FWHM) of AlScN(002) rocking curves at 2.2 ± 0.1° over the whole coating area when deposited with higher share of unipolar pulse mode during film growth. For a higher share of bipolar pulse mode, the films showed a much larger c-lattice parameter in the center of the coating area, indicating high in-plane compressive stress in the films. Rocking curve FWHM also showed similar values of 1.5° at the center to 3° at outer edge. The piezoelectric characterization method revealed homogenous d33,f of 11–12 pm/V for films deposited at a high share of unipolar pulse mode and distribution of 7–10 pm/V for a lower share of unipolar pulse mode. The films exhibited ferroelectric switching behavior with coercive fields of around 3–3.5 MV/cm and polarization of 80–120 µC/cm².

A time-sequential working, spatially-multiplexed autostereoscopic 3D display design consisting of a fast switchable RGB-color filter array and a fast color display is presented. The newly-introduced 3D display design is usable as a multi-user display, as well as a single-user system. The wavelength-selective filter barrier emits the light from a larger aperture than common autostereoscopic barrier displays with similar barrier pitch and ascent. Measurements on a demonstrator with commercial display components, simulations and computational evaluations have been carried out to describe the proposed wavelength-selective display design in static states and to show the weak spots of display filters in commercial displays. An optical modelling of wavelength-selective barriers has been used for instance to calculate the light ray distribution properties of that arrangement. In the time-sequential implementation, it is important to avoid that quick eye or eyelid movement leads to visible color artifacts. Therefore, color filter cells, switching faster than conventional LC display cells, must distribute directed light from different primaries at the same time, to create a 3D presentation. For that, electric tunable liquid crystal Fabry–Pérot color filters are presented. They switch on-off the colors red, green and blue in the millisecond regime. Their active areas consist of a sub-micrometer-thick nematic layer sandwiched between dielectric mirrors and indium tin oxide (ITO)-electrodes. These cells shall switch narrowband light of red, green or blue. A barrier filter array for a high resolution, glasses-free 3D display has to be equipped with several thousand switchable filter elements having different color apertures.

This paper reports on the deposition of AlN and Al X Sc 1−X N films by pulse magnetron sputtering. The first part will focus on the Al X Sc 1−X N deposition process in comparison to the already established AlN process. The effect of doping AlN with Sc regarding piezoelectric and mechanical properties is presented. The films show the expected increase of piezoelectric properties as well as the softening of the material with higher Sc concentrations. Above a threshold concentration of around 40 % Sc in the Al X Sc 1−X N films, there exists a separation into two phases, an Al-rich and a Sc-rich wurtzite phase, which is shown by XRD. At Sc concentrations higher than 50 %, the films are not piezoelectric, as the films are composed primarily of the cubic ScN phase. The second main part of this paper evaluates the films for application in energy harvesting. Especially the Sc doping allows a significant increase in the energy generated in our test setup. Directly measuring the AC voltage at resonance depending on load resistance with base excitation of ±2.5 µm, 350 µW power have been generated under optimum conditions compared to 70 µW for pure AlN. For a more application oriented measuring setup, a standard and a SSHI-based (“Synchronised Switch Harvesting on Inductor”) AC/DC converter circuit have been tested. The SSHI interface showed a significant improvement to 180 % compared to the standard interface.

In this paper specific advantages and disadvantages of different pulse magnetron sputtering processes (unipolar, bipolar and HIPIMS) as well as current and potential fields of application will be discussed. On the examples of ZrN, Ti and TiO2 the typical effects and their influence on film properties occurring during the transition from classical medium frequency pulse magnetron sputtering to high energy pulse sputtering will be described. The discharge current density was varied between 0.2 and 3.5 A/cm2. Aspects of energy feed-in and reactive process control in the transition mode will be considered. Furthermore the influence of rising ionisation on the occurrence of crystalline phases and on mechanical, optical and photocatalytic properties of the layers will be presented. The paper concludes with a placement of the processes related to other PVD-processes that is based on further own experimental results and evaluation of dependencies as well as considering published results of other groups regarding pulse magnetron sputter processes of high power density for the deposition of hard coatings and TCO.