Versatile Large-Area Custom-Feature van der Waals Epitaxy of Topological Insulators.

As the focus of applied research in topological insulators (TI) evolves, the need to synthesize large-area TI films for practical device applications takes center stage. However, constructing scalable and adaptable processes for high-quality TI compounds remains a challenge. To this end, a versatile van der Waals epitaxy (vdWE) process for custom-feature bismuth telluro-sulfide TI growth and fabrication is presented, achieved through selective-area fluorination and modification of surface free-energy on mica.

Large-Area Dry Transfer of Single-Crystalline Epitaxial Bismuth Thin Films.

We report the first direct dry transfer of a single-crystalline thin film grown by molecular beam epitaxy. A double cantilever beam fracture technique was used to transfer epitaxial bismuth thin films grown on silicon (111) to silicon strips coated with epoxy. The transferred bismuth films retained electrical, optical, and structural properties comparable to the as-grown epitaxial films.

Air Stable Doping and Intrinsic Mobility Enhancement in Monolayer Molybdenum Disulfide by Amorphous Titanium Suboxide Encapsulation.

To reduce Schottky-barrier-induced contact and access resistance, and the impact of charged impurity and phonon scattering on mobility in devices based on 2D transition metal dichalcogenides (TMDs), considerable effort has been put into exploring various doping techniques and dielectric engineering using high-κ oxides, respectively. The goal of this work is to demonstrate a high-κ dielectric that serves as an effective n-type charge transfer dopant on monolayer (ML) molybdenum disulfide (MoS2). Utilizing amorphous titanium suboxide (ATO) as the "high-κ dopant", we achieved a contact resistance of ∼180 Ω·μm that is the lowest reported value for ML MoS2.