Seeding 2D crystals: Small, single crystals are often used to direct the growth of larger, bulk single crystals. Xu et al. modified these methods to grow single-crystal films of a two-dimensional (2D) semiconductor, 2H molybdenum ditelluride (2H MoTe ₂ ), on an amorphous glass surface. After coating the wafer with a 1T′ MoTe ₂ film, a small 2H MoTe ₂ crystallite was placed on the wafer. The wafer was capped with an alumina film, except for a small hole above the seed region that allowed entry of additional tellurium during the heating process that drove the phase transition and epitaxial growth of 2H MoTe ₂ . Science , this issue p. 195

The controllable fabrication of patterned p-type and n-type channels with precise doping control presents a significant challenge, impeding the realization of complementary metal-oxide-semiconductor (CMOS) logic using a single van der Waals material. However, such an achievement could offer substantial benefits by enabling continued transistor scaling and unprecedented interlayer interconnect technologies. In this study, we devise a precise method for two-dimensional (2D) semiconductor substitutional doping, which allows for the production of wafer-scale 2H-MoTe₂ thin films with specific p-type or n-type doping. Notably, we extend this approach to the synthesis of spatially selective doped 2H-MoTe₂ thin films via a one-step growth method, facilitating the monolithic integration of p-type and n-type semiconductor channels. Leveraging this advancement, we successfully fabricate a chip-sized 2D CMOS inverter array that demonstrates excellent device performance and yield. Collectively, these findings represent a significant stride towards the practical incorporation of 2D semiconductors in very large-scale integration technology.

Due to complex thermodynamic and kinetic mechanism, phase engineering in nanomaterials is often limited by restricted phases and small-scale synthesis, hindering material diversity and scalability. Here, we demonstrate the exploration to unlock the stoichiometry as a degree of freedom for phase engineering in the Pd-Te binary compound. By reducing diffusion rates, we effectively engineer the stoichiometry of the reactants. We visualize the kinetic process, showing the stoichiometry transition from Pd₁₀Te₃ to PdTe₂ through a sequential multi-step nucleation process. In total, five distinct phases are identified, demonstrating the potential to enhance phase diversity by fine-tuning stoichiometry. By controlling spatially uniform nucleation and halting the phase transition at precise points, we achieve stoichiometry-controllable wafer-scale growth. Notably, four of these phases exhibit superconducting properties. Our findings offer insights into the mechanism of phase transition through stoichiometry engineering, enabling the expansion of the phase library in nanomaterials and advancing scalable applications.

In recent years, there has been a growing fascination with suspended two-dimensional (2D) materials, owing to their excellent mechanical, optical, and electronic characteristics. This surge of interest stems from the remarkable properties exhibited by these materials when they are isolated in a two-dimensional counterpart. Nanofabrication technologies provide a new platform to further explore the properties of 2D materials by suspending them to reduce the influence of substrates. In recent years, many scientists have discovered the feasibility of using suspended membranes of 2D materials in various fields, including optoelectronics and photonics. This review summarizes the recent progress in the fabrication, characterization, and applications of suspended 2D materials, focusing on critical properties such as optical and electronic properties, strain engineering, and thermal properties. This area has the potential to lead to new technologies and applications in a wide range of innovative fields.