Titanium gold

Abstract: Stable ohmic contacts are critical to enable efficient operation of high-voltage electronic devices using ultrawide bandgap semiconductors. Here we perform, for the first time, thermally accelerate...

Abstract: Here, we study the kinetic evolution of the interface between a Ti/Au metal stack and bulk (010) β-Ga2O3 substrate under different annealing conditions using scanning / transmission electron microscopy. We observe distinct processes of interfacial reaction and interdiffusion between the metal films and at the metal-semiconductor junction. Upon rapid thermal annealing (RTA), the as-deposited Ti readily reacts at the β-Ga2O3 interface, driven by redox favorability. After a 1-min 470°C N2 RTA, the interface exhibits two segregated crystalline layers: a ∼5 nm Ti-rich (Ti-TiOx) layer lattice-matched to the β-Ga2O3 substrate and a ∼3 nm Ga-rich (TiGax) layer. A substitutional mechanism is proposed based on the similarity in ionic radii of Ti+3, Ti+4, and Ga+3. After 15-min RTA, the Ga-rich layer is diluted within the Ti-Au matrix, while the Ti-TiOx layer does not significantly change, and there is no further observable Ga out-diffusion from the substrate. Thus, we propose that the Ti-TiOx layer acts as a diffusion barrier, even when it is no longer lattice-matched with β-Ga2O3. In addition, Ti-rich nanocrystals form within the Ti-Au layer, presumably via the proceeding reactions. The observations here provide insights for contact stack evolution during operation of power electronic devices at elevated temperature. © The Author(s) 2019. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. [DOI: 10.1149/2.0321907jss]

Abstract: Investigations in the binary system gold-titanium (Au-Ti) were performed in regard to the development of a universal dental alloy suited for inlays, for the conventional crown and bridge technique, as well as for the ceramic-fused-to-metal technique. With nine alloys with increasing Ti content from 0–10 atom %, microstructure, mechanical properties, thermal properties, and corrosion were determined in the as-cast state and after simulation of ceramic firing. The microstructure shows an increasing formation of a second phase with increasing Ti content, crystallizing dendritically, which, according to the binary phase diagram must be the intermetallic phase TiAu4. The results of the measurements reveal that with increasing Ti content, hardness, Young's modulus, proof stress, and tensile strength strongly increase in the range of 2–6 atom % Ti and with higher Ti content remain constant. Elongation after fracture decreases with a Ti content above 2 atom %. The coefficient of thermal expansion decreases linearly with increasing Ti content. Thermal distortion decreases exponentially with increasing Ti content. The corrosion test showed an increasing release of Ti with increasing Ti content. Lowest corrosion was observed in the simulated state with intact oxide layer. Appropriate properties for dental application were found in the range of 6.5 at% Ti. © 2000 John Wiley & Sons, Inc. J Biomed Mater Res, 52, 678–686, 2000.