Application of Micro Slurry-Jet Erosion (MSE) for the Evaluation of Surface Properties of PVD TiN / TiCN Two-Layer Coatings

In this study, the potential of a Micro Slurry-jet Erosion (MSE) test to swiftly evaluate the intrinsic surface strength properties of thin multi-layer coatings is demonstrated. A slurry containing 1.2 μm alumina particles was impacted at high velocity perpendicular to PVD TiN/TiCN (TiCN on top of TiN) and TiN coatings deposited on high-speed steel by a hollow cathode discharge (HCD) or an cathodic arc (CA) method. In addition, nano-indentation and XRD, GDOES analyses were done for the original surfaces. By measuring the variation of erosion depth against test time, the MSE test made it possible to evaluate the individual erosion properties of TiCN and TiN layers independent of the substrate. Although the hardness of TiCN layers, coated by HCD or CA, was measured with nano-indentation and found to be approximately 20% higher than for TiN, the erosion rates of TiCN layers were found to be between 32% and 38% of the erosion rate of TiN. For the HCD coating, the erosion proceeded uniformly and produced a mostly smooth surface. On the other hand, for the CA coating, a pitted surface was observed. The existence of the hollows blemishes which caused by macroparticles i. e. droplets in the coating may affect the difference in the erosion rates between HCD and CA coatings. Consequently, the MSE test may be useful to evaluate the difference of the morphology of coatings as well as the surface strength which are related with the fabrication process

Cryogenic Integration for Quantum Computer Using Diamond Color Center Spin Qubits

For quantum computing modules using diamond color centers, we propose an integrated structure of a quantum chip with photonic circuits and an interposer with electric circuits. The chip and interposer are connected via gold stud bumps using flip-chip bonding technology. For evaluating the proposed integrated structure, we bonded a test chip of 15 × 15 mm2, corresponding to the area that allows the allocation of color center qubits in the order of 102, with an interposer of 20 × 20 mm2, including test measurement lines. We confirm all connections of 16 lines with two bumps for each line at 10 K. The resistance of the lines with two bumps at 10 K is ~ 3.5O, These resistances are mainly attributed to the gold lines on the interposer, which is confirmed by simulations. The shear strength of the flip-chip bonded structure is 67 g/bump. It is larger than that of previous reports where the chips passed the standard temperature cycle test. Moreover, we integrate the flip-chip bonded structure with a printed circuit board (PCB). We confirm a connection between the connector terminal of the PCB and the test chip at 80 K. It is shown that the integrated structure using gold stud bumps has a potentially highly reliable connection at cryogenic temperature. These results will lead to realizing large-scale diamond spin quantum processors. Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.QID/Ishihara LabQuantum Circuit Architectures and Technolog

Surface-activated direct bonding of diamond (100) and c-plane sapphire with high transparency for quantum applications

Surface-activated direct bonding of diamond (100) and c-plane sapphire substrates is investigated using Ar atom beam irradiation and high-pressure contact at RT. The success probability of bonding strongly depends on the surface properties, i.e, atomic smoothness for the micron-order area and global flatness for the entire substrate. Structural analysis reveals that transformation from sapphire to Al-rich amorphous layer is key to obtaining stable bonding. The beam irradiation time has optimal conditions for sufficiently strong bonding, and strong bonding with a shear strength of more than 14 MPa is successfully realized. Moreover, by evaluating the photoluminescence of nitrogen-vacancy centers in the diamond substrate, the bonding interface is confirmed to have high transparency in the visible wavelength region. These results indicate that the method used in this work is a promising fabrication platform for quantum modules using diamonds.Safety and Security ScienceQuantum Circuit Architectures and TechnologyQID/Ishihara La