Van der Waals heterostructures and devices

Schottky-Barrier-Free Contacts with Two-Dimensional Semiconductors by Surface-Engineered MXenes

“…[14][15][16] Very recently, the use of Ti 2 CT x as electrodes for 2D MoS 2 and WSe 2 field effect transistors have been experimentally demonstrated, yet with significant SBs 17 . Here we predict that SB-free contacts can be achieved by using MXenes with proper surface terminations, which form van der Waals (vdW) junctions 16,18,19 with 2D semiconductors. We also suggest synthetic routes to control the surface termination based on the calculated formation energies.…”

Recent progress in the assembly of nanodevices and van der Waals heterostructures by deterministic placement of 2D materials

“…The PMMA is then attached to a glass slide connected to a micromanipulator with the flake facing down (4). With the help of a microscope the flake is aligned with the target substrate and is then brought in contact (5). By gently separating the PMMA from the final substrate the flake get transferred.…”

“…The substrate is immersed in water (3) and a layer of water is intercalated (wedged) between the hydrophilic SiO2 and the hydrophobic polymer carrying the flake delaminating the polymer film that remains floating at the water/air interface. The transfer of the flake is achieved by pumping down the water (4), which lowers the water level and brings the polymer in contact with a target substrate lying below (5). To align the flake with the target substrate, a needle coupled to a micromanipulator can be used to gently position the floating polymer at will.…”

“…(4). By pumping down the water the two can be brought in contact (5). Then the polymer can be dissolved leaving the flake transferred onto the final substrate (6).…”

Active 2D materials for on-chip nanophotonics and quantum optics

“…They can be conformally layered with relative ease and are "glued" sufficiently strongly by van der Waals (vdW) forces. The advent of such vdW material platforms has proven extremely rich and fruitful for not only electronic [6] but also photonic devices and systems [7]. The primary applications of vdW materials integrated into PICs are in optical interconnects and quantum information processing.…”