Yanli Wang

Bio: Yanli Wang is an academic researcher from Zhejiang Sci-Tech University. The author has contributed to research in topics: Boron nitride & Band gap. The author has an hindex of 19, co-authored 29 publications receiving 1732 citations. Previous affiliations of Yanli Wang include Tsinghua University.

First principles study of structural, vibrational and electronic properties of graphene-like MX2 (M=Mo, Nb, W, Ta; X=S, Se, Te) monolayers

Abstract: Using first principles calculations, we investigate the structural, vibrational and electronic structures of the monolayer graphene-like transition-metal dichalcogenide (MX2) sheets. We find the lattice parameters and stabilities of the MX2 sheets are mainly determined by the chalcogen atoms, while the electronic properties depend on the metal atoms. The NbS2 and TaS2 sheets have comparable energetic stabilities to the synthesized MoS2 and WS2 ones. The molybdenum and tungsten dichalcogenide (MoX2 and WX2) sheets have similar lattice parameters, vibrational modes, and electronic structures. These analogies also exist between the niobium and tantalum dichalcogenide (NbX2 and TaX2) sheets. However, the NbX2 and TaX2 sheets are metals, while the MoX2 and WX2 ones are semiconductors with direct-band gaps. When the Nb and Ta atoms are doped into the MoS2 and WS2 sheets, a semiconductor-to-metal transition occurs. Comparing to the bulk compounds, these monolayer sheets have similar structural parameters and properties, but their vibrational and electronic properties are varied and have special characteristics. Our results suggest that the graphene-like MX2 sheets have potential applications in nano-electronics and nano-devices.

Density Functional Theory Study of the Silicene-like SiX and XSi3 (X = B, C, N, Al, P) Honeycomb Lattices: The Various Buckled Structures and Versatile Electronic Properties

Abstract: Using the density functional theory calculations, we systematically investigate the structures and properties of silicene-like SiX and XSi3 (X = B, C, N, Al, P) hexagonal heterosheets. For the SiX systems, the SiP sheet favors a chairlike buckled structure akin to silicene, the SiB, SiN, and SiAl ones prefer the washboard-like buckling type, and the SiC sheet adopts the flat plane as graphene. The planarity is also favored in the XSi3 sheets with X = B, C, Al, while the rests with X = N and P prefer the chairlike buckled structures. The energetic stabilities and mechanical properties are also investigated for these SiX and XSi3 systems, and all the heterosheets are found to be stable. Unlike the semimetallic silicene, most of the SiX sheets are transformed to metals except for the SiC one with a wide band gap. For the XSi3 systems, they can be metals, semimetals, or narrow-band gap semiconductors depending on the X elements. The BSi3 and NSi3 sheets exhibit metallic behaviors, which behave like the p-type...

Structural, Electronic, and Magnetic Properties of Adatom Adsorptions on Black and Blue Phosphorene: A First-Principles Study

Abstract: Using first-principles calculations, we investigate the adsorption characteristics of alkali, alkaline-earth, nonmetallic, transition, and noble metal adatoms on phosphorene. The adsorption-induced tunable electronic structures are comparatively studied on two representative structures of phosphorene, i.e., black and blue phosphorus (P) nanosheets. Both black and blue P sheets exhibit good adsorption capability to foreign atoms, on which the binding energies of adatoms are stronger than on the BN, SiC, MoS2, or graphene sheets. On the black P sheet, most adatoms prefer to adsorb on the hollow site, whereas for the blue P sheet, the favored adsorption sites are element-dependent. The majority of alkali, alkaline-earth, and transition-metal adatoms prefer the valley site, noble metal adatoms the hollow site, and nonmetallic adatoms the bridge and top sites instead. The semiconducting behaviors of phosphorene are modified by adatoms, which can cause p-type and n-type doping or induce midgap states into the P...

Electronic Structure and Carrier Mobilities of Arsenene and Antimonene Nanoribbons: A First-Principle Study

Abstract: Arsenene and antimonene, i.e. two-dimensional (2D) As and Sb monolayers, are the recently proposed cousins of phosphorene (Angew. Chem. Int. Ed., 54, 3112 (2015)). Through first-principle calculations, we systematically investigate electronic and transport properties of the corresponding As and Sb nanoribbons, which are cut from the arsenene and antimonene nanosheets. We find that different from the 2D systems, band features of As and Sb nanoribbons are dependent on edge shapes. All armchair As/Sb nanoribbons keep the indirect band gap feature, while the zigzag ones transfer to direct semiconductors. Quantum confinement in nanoribbons enhances the gap sizes, for which both the armchair and zigzag ones have a gap scaling rule inversely proportional to the ribbon width. Comparing to phosphorene, the large deformation potential constants in the As and Sb nanoribbons cause small carrier mobilities in the orders of magnitude of 101–102 cm2/Vs. Our study demonstrates that the nanostructures of group-Vb elements would possess different electronic properties for the P, As, and Sb ones, which have diverse potential applications for nanoelectronics and nanodevices.

Electronic properties of graphene nanoribbons embedded in boron nitride sheets

Abstract: Using first principles calculations, we investigate the stabilities and electronic properties of graphene nanoribbons which are embedded in boron nitride (BN) sheets. We find that carbon atoms doped in BN sheets have stable hexagonal configurations and can form one-dimensional nanoribbons under suitable chemical potential conditions. All the armchair graphene nanoribbons embedded in BN sheets are semiconductors. While for the zigzag ones, the wide nanoribbons become half-metals.

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides.

Abstract: Single-layer metal dichalcogenides are two-dimensional semiconductors that present strong potential for electronic and sensing applications complementary to that of graphene.

Progress, Challenges, and Opportunities in Two-Dimensional Materials Beyond Graphene

Abstract: Graphene’s success has shown that it is possible to create stable, single and few-atom-thick layers of van der Waals materials, and also that these materials can exhibit fascinating and technologically useful properties. Here we review the state-of-the-art of 2D materials beyond graphene. Initially, we will outline the different chemical classes of 2D materials and discuss the various strategies to prepare single-layer, few-layer, and multilayer assembly materials in solution, on substrates, and on the wafer scale. Additionally, we present an experimental guide for identifying and characterizing single-layer-thick materials, as well as outlining emerging techniques that yield both local and global information. We describe the differences that occur in the electronic structure between the bulk and the single layer and discuss various methods of tuning their electronic properties by manipulating the surface. Finally, we highlight the properties and advantages of single-, few-, and many-layer 2D materials in...

Recent Advances in Two-Dimensional Materials beyond Graphene

Abstract: The isolation of graphene in 2004 from graphite was a defining moment for the “birth” of a field: two-dimensional (2D) materials In recent years, there has been a rapidly increasing number of papers focusing on non-graphene layered materials, including transition-metal dichalcogenides (TMDs), because of the new properties and applications that emerge upon 2D confinement Here, we review significant recent advances and important new developments in 2D materials “beyond graphene” We provide insight into the theoretical modeling and understanding of the van der Waals (vdW) forces that hold together the 2D layers in bulk solids, as well as their excitonic properties and growth morphologies Additionally, we highlight recent breakthroughs in TMD synthesis and characterization and discuss the newest families of 2D materials, including monoelement 2D materials (ie, silicene, phosphorene, etc) and transition metal carbide- and carbon nitride-based MXenes We then discuss the doping and functionalization of 2

Band offsets and heterostructures of two-dimensional semiconductors

Abstract: The band offsets and heterostructures of monolayer and few-layer transition-metal dichalcogenides MX2 (M = Mo, W; X = S, Se, Te) are investigated from first principles calculations. The band alignments between different MX2 monolayers are calculated using the vacuum level as reference, and a simple model is proposed to explain the observed chemical trends. Some of the monolayers and their heterostructures show band alignments suitable for potential applications in spontaneous water splitting, photovoltaics, and optoelectronics. The strong dependence of the band offset on the number of layers also implicates a possible way of patterning quantum structures with thickness engineering.