We investigate the geometric, electric, and optical properties of two-dimensional honeycomb lattices using first-principles simulations. The main focus of this work is on the similarities and differences in their characteristics, as well as the delicate connection of orbital hybridizations and spin-polarizations with electronic and optical properties. Graphene, silicene, germanene, and their semi-hydrogenated systems, in turn, display sp², sp²–sp³, and sp³s hybridizations. These bonding configurations are critical factors affecting the geometric structure, the electronic band structure, van Hove singularities in density of states, the magnetic configurations, the dielectric functions, and energy loss functions. Furthermore, the meta-stable and stable exciton states are expected to survive in pristine and semi-hydrogenated group IV monolayers, respectively. The theoretical predictions established in this work are important not only for basic science but also for high-tech applications.

Adjusting the orientation of the sapphire substrate to align the gas flow direction in the NaCl-assisted CVD process can improve the stability of monolayer WS ₂ .

Ferroelectricity realized in van der Waals (vdW) materials with non‐centrosymmetric stacking configurations holds promise for future 2D devices with nonvolatile and reconfigurable functionalities. However, the epitaxial growth of ferroelectric vdW materials often struggles to achieve an energetically unfavorable stacking configuration that enables electric polarization. This challenge is particularly evident when performing heteroepitaxy on another vdW substrate to create versatile and scalable ferroelectric building blocks designed for large‐area, atomic‐scale thicknesses. Here, epitaxial hexagonal boron nitride (h‐BN) multilayer films are successfully grew on single‐crystal graphene synthesized on a miscut SiC (0001) substrate. Theoretical calculations illustrate that the moiré‐patterned h‐BN/graphene hetero‐interface intrinsically exhibits polarization, leading to a polarized AB stacking in multilayer h‐BN films to minimize the total formation energy, which is validated experimentally by the layer‐dependent band dispersions. The as‐grown multilayer h‐BN layers demonstrated robust, homogeneous ferroelectricity with switchable out‐of‐plane polarization via interlayer sliding. This study establishes an effective route for stacking‐controlled heteroepitaxy, enabling the large‐scale integration of vdW materials with ferroelectricity and versatile functionalities, offering a promising platform for next‐generation 2D ferroelectric devices.

WO_x conversion for doping is highlighted in recent advancements in WSe₂ p-FETs. While past studies focused on exfoliated WSe₂ flakes, our research examines CVD-grown WSe₂ films, assessing the impact of this doping on channel mobility and contact resistance in devices. Our approach enables effective threshold voltage tuning in both n- and p-type FETs with various low-dimensional material channels with the doping mechanism well captured by TCAD simulations. When applied to WSe₂, trilayer devices exhibited a good and comparable median field-effect mobility of 65 cm²/V·s following the conversion process. Consequently, trilayer WSe₂ was used to demonstrate top-gated p-MOSFETs via self-aligned WO_x conversion in the spacer region, achieving a 250-fold enhancement in the on-current while maintaining a subthreshold swing of 80 mV/dec. Our findings provide a comprehensive understanding of WO_x conversion and its general applicability, paving the way for its use in future logic devices with low-dimensional materials.