Layer-by-layer graphene growth is demonstrated by repeating CVD growth cycles directly on sapphire substrates. Improved field-effect mobility values are observed for the bottom-gate transistors fabricated by using the bilayer graphene channel, which indicates an improved crystallinity is obtained after the second CVD growth cycle. Despite the poor wettability of copper on graphene surfaces, graphene may act as a thin and effective diffusion barrier for copper atoms. The low resistivity values of thin copper films deposited on thin monolayer MoS 2 /monolayer graphene heterostructures have demonstrated its potential to replace current thick liner/barrier stacks in back-end interconnects. The unique van der Waals epitaxy growth mode will be helpful for both homo- and heteroepitaxy on 2D material surfaces.

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We propose and demonstrate an improved method for transfer printing that allows for the accurate docking of a photonic crystal nanobeam (NB) laser onto a SiN x waveguide. Our proposed method enables achieving much smaller transfer printing misalignments compared to the conventional approach based on visual alignment in experiments. We tested our method by docking a modified NB laser design with a theoretical unidirectional coupling efficiency of 64% to the SiN x waveguide. The results show a mean rotational misalignment of only 0.08°and a mean displacement misalignment of 26 nm for 48 NB lasers docked at the SiN x waveguides, demonstrating the high accuracy and excellent transfer printing reproducibility of our proposed method. Additionally, measurements indicated that over 97% of these highly accurate docked NB lasers exhibited uniform unidirectional coupling to specific waveguide output facets. We believe that the improved transfer printing steps presented in this study, along with the corresponding hybrid integration of docking NB lasers at the SiN x waveguide, provide a highly promising method for accurately integrating nanowire-based light sources into silicon-based photonic integrated circuits.

Recent development of particle manipulation has led to high demand for dynamic optical tweezers structures. However, confining and rotating single microparticle in the far-field region with uniform potential distribution remains...