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- ItemThe role of substrate temperature and magnetic filtering for DLC by cathodic arc evaporation(Basel : MDPI, 2019) Lux, Helge; Edling, Matthias; Lucci, Massimiliano; Kitzmann, Julia; Villringer, Claus; Siemroth, Peter; De Matteis, Fabio; Schrader, SigurdDiamond-like carbon (DLC) films were deposited using two different types of high current arc evaporation. The first process used a magnetic particle filter to remove droplets from the plasma. For the second process, the samples were put into a metallic cage which was placed directly above the plasma source. For both processes, we varied the substrate temperature from 21 to 350 °C in order to investigate the temperature effect. The samples were characterized using SEM, AFM, XPS, Raman Spectroscopy, Ellipsometry, Photometry, and Nano Indentation in order to compare both methods of deposition and provide a careful characterization of such DLC films. We found that the sp3 content and the hardness can be precisely adjusted by changing the substrate temperature. Furthermore, in the case of unfiltered deposition, the optical constants can be shifted in the direction of higher absorbance in order to produce black and hard carbon coatings. © 2019 by the authors.
- ItemThin film deposition using energetic ions(Basel : MDPI, 2010) Manova, D.; Gerlach, J.W.; Mändl, S.One important recent trend in deposition technology is the continuous expansion of available processes towards higher ion assistance with the subsequent beneficial effects to film properties. Nowadays, a multitude of processes, including laser ablation and deposition, vacuum arc deposition, ion assisted deposition, high power impulse magnetron sputtering and plasma immersion ion implantation, are available. However, there are obstacles to overcome in all technologies, including line-of-sight processes, particle contaminations and low growth rates, which lead to ongoing process refinements and development of new methods. Concerning the deposited thin films, control of energetic ion bombardment leads to improved adhesion, reduced substrate temperatures, control of intrinsic stress within the films as well as adjustment of surface texture, phase formation and nanotopography. This review illustrates recent trends for both areas; plasma process and solid state surface processes. © 2010 by the authors.
- ItemEpitaxial growth and stress relaxation of vapor-deposited Fe-Pd magnetic shape memory films(College Park, MD : Institute of Physics Publishing, 2009) Kühnemund, L.; Edler, T.; Kock, I.; Seibt, M.; Mayr, S.G.To achieve maximum performance in microscale magnetic shape memory actuation devices epitaxial films several hundred nanometers thick are needed. Epitaxial films were grown on hot MgO substrates (500 °C and above) by e-beam evaporation. Structural properties and stress relaxation mechanisms were investigated by high-resolution transmission electron microscopy, in situ substrate curvature measurements and classical molecular dynamics (MD) simulations. The high misfit stress incorporated during Vollmer-Weber growth at the beginning was relaxed by partial or perfect dislocations depending on the substrate temperature. This relaxation allowed the avoidance of a stressinduced breakdown of epitaxy and no thickness limit for epitaxy was found. For substrate temperatures of 690 °C or above, the films grew in the fee austenite phase. Below this temperature, iron precipitates were formed. MD simulations showed how these precipitates influence the movements of partial dislocations, and can thereby explain the higher stress level observed in the experiments in the initial stage of growth for these films. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
- ItemSubstrate-orientation dependence of β -Ga2O3 (100), (010), (001), and (2 ̄ 01) homoepitaxy by indium-mediated metal-exchange catalyzed molecular beam epitaxy (MEXCAT-MBE)(Melville, NY : AIP Publ., 2020) Mazzolini, P.; Falkenstein, A.; Wouters, C.; Schewski, R.; Markurt, T.; Galazka, Z.; Martin, M.; Albrecht, M.; Bierwagen, O.We experimentally demonstrate how In-mediated metal-exchange catalysis (MEXCAT) allows us to widen the deposition window for β-Ga2O3 homoepitaxy to conditions otherwise prohibitive for its growth via molecular beam epitaxy (e.g., substrate temperatures ≥800 °C) on the major substrate orientations, i.e., (010), (001), (2⎯⎯01), and (100) 6°-offcut. The obtained crystalline qualities, surface roughnesses, growth rates, and In-incorporation profiles are shown and compared with different experimental techniques. The growth rates, Γ, for fixed growth conditions are monotonously increasing with the surface free energy of the different orientations with the following order: Γ(010) > Γ(001) > Γ(2⎯⎯01) > Γ(100). Ga2O3 surfaces with higher surface free energy provide stronger bonds to the surface ad-atoms or ad-molecules, resulting in decreasing desorption, i.e., a higher incorporation/growth rate. The structural quality in the case of (2⎯⎯01), however, is compromised by twin domains due to the crystallography of this orientation. Notably, our study highlights β-Ga2O3 layers with high structural quality grown by MEXCAT-MBE not only in the most investigated (010) orientation but also in the (100) and (001) ones. In particular, MEXCAT on the (001) orientation results in both growth rate and structural quality comparable to the ones achievable with (010), and the limited incorporation of In associated with the MEXCAT deposition process does not change the insulating characteristics of unintentionally doped layers. The (001) surface is therefore suggested as a valuable alternative orientation for devices.