Jenq-Horng Liang

Plasma-Assisted Synthesis of High-Mobility Atomically Layered Violet Phosphorus

Two-dimensional layered materials such as graphene, transition metal dichalcogenides, and black phosphorus have demonstrated outstanding properties due to electron confinement as the thickness is reduced to atomic scale. Among the phosphorus allotropes, black phosphorus, and violet phosphorus possess layer structure with the potential to be scaled down to atomically thin film. For the first time, the plasma-assisted synthesis of atomically layered violet phosphorus has been achieved. Material characterization supports the formation of violet phosphorus/InN over InP substrate where the layer structure of violet phosphorus is clearly observed. The identification of the crystal structure and lattice constant ratifies the formation of violet phosphorus indeed. The critical concept of this synthesis method is the selective reaction induced by different variations of Gibbs free energy (ΔG) of reactions. Besides, the Hall mobility of the violet phosphorus on the InP substrate greatly increases over the theoretical values of InP bulk material without much reduction in the carrier concentration, suggesting that the mobility enhancement results from the violet phosphorus layers. Furthermore, this study demonstrates a low-cost technique with high compatibility to synthesize the high-mobility atomically layered violet phosphorus and open the space for the study of the fundamental properties of this intriguing material as a new member of the fast growing family of 2D crystals.

Fabrication of Multilayer Borophene on Insulator Structure

The X-ray photoelectron spectroscopy spectra indicate the peak of Buf8ffB bonds, implying that the elemental boron structure might be formed after the process. The multilayer β-borophene is directly observed by transmission electron microscopy (TEM) and the lattice parameters are valid. The middle SiNx layer also can be identified in TEM image. Furthermore, the 1.61 eV bandgap of the multilayer β-borophene is announced in this study.

Vertical Al2Se3/MoSe2 heterojunction on sapphire synthesized using ion beam

The vertical Al2Se3/MoSe2 heterojunction on sapphire was first fabricated via an ion beam-assisted process. The MoSe2 was formed via Mo selenization, while Al2Se3 was formed via Se substitution for O in sapphire. The applications of this heterojunction will be developed in the future.