Speaker
Description
Cavity-enhanced diamond color-center qubits can be initialized, manipulated, entangled, and read individually with high fidelity, which makes this scheme ideal for implementing large-scale, modular quantum computers, quantum networks, and distributed quantum sensing systems [1 - 3]. However, the limited size of heteroepitaxially grown single-crystal diamond poses challenges for its integration into existing manufacturing processes. In this work, we have developed a direct bonding approach that enables the bonding of (100) single-crystal diamond membranes to various carrier wafers, including plasma-enhanced chemical vapor deposition oxide and thermal oxide with different surface roughness. We have developed established a recipe for bonding thin (< 50 μm) (100) diamond plates SiO2/Si substrates with high yield (90 %) and bonding strength around 2MPa. We employ surface characterization techniques to investigate the key factors influencing the quality of direct bonding. We also use X-ray photoelectron spectroscopy for quantitative analysis of the surface chemicals at the bonding interface, aiding in the optimization of process parameters [4]. Furthermore, we have bonded 10 μm diamond plates to SiO2/Si substrates and thinned the diamond down to produce a photonic grade (thickness < 300 nm) DOI substrate. We achieved a DOI film of uniform thickness less than 300 nm over an area of 0.5 × 0.5 mm² and surface roughness below 0.5 nm, while preserving the bonding interface intact. The DOI substrate developed in this work provides a platform for scalable fabrication of diamond nanophotonic devices and helps us realize an all-diamond integrated quantum system [1, 2].
We gratefully acknowledge support from the joint research program “Modular quantum computers” by Fujitsu Limited and Delft University of Technology, co-funded by the Netherlands Enterprise Agency under project number PPS2007.
[1] Ishihara, Ryoichi, et al. "3D Integration Technology for Quantum Computer based on Diamond Spin Qubits." IEEE International Electron Devices Meeting (IEDM) (2021).
[2] Shandilya, Prasoon K., et al. "Diamond Integrated Quantum Nanophotonics: Spins, Photons and Phonons." Journal of Lightwave Technology 40. 23 (2022).
[3] Ruf, Maximilian, et al. "Quantum networks based on color centers in diamond." Journal of Applied Physics 130.7 (2021).
[4] Manuscript in preparation.
