Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userOut-of-plane structural flexibility of phosphorene
69
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Phosphorene has been rediscovered recently, establishing itself as one of the most promising two dimensional group-V elemental monolayers with direct band gap, high carrier mobility, and anisotropic electronic properties. In this letter, the buckling and its effect on the electronic properties in phosphorene are investigated by using molecular dynamics simulations and complemented by density functional theory calculations. We find that phosphorene shows superior out-of-plane structural flexibility along the armchair direction, which allows the formation of buckling with large curvatures, while the buckling along the zigzag direction will break its structure integrity at large curvatures. The semiconducting and direct band gap nature are retained with buckling along the armchair direction; the band gap decreases and transforms to an indirect band gap with buckling along the zigzag direction. The structural flexibility and electronic robustness along the armchair direction facilitate the fabrication of devices with complex shapes, such as folded phosphorene and phosphorene nano-scrolls, thereby offering new possibilities for the application of phosphorene in flexible electronics and optoelectronics.
rate research
Read More
We systematically explore chemical functionalization of monolayer black phosphorene via chemisorption of oxygen and fluorine atoms. Using the cluster expansion technique, with vary- ing concentration of the adsorbate, we determine the ground states considering both single- as well as double- side chemisorption, which have novel chemical and electronic properties. The nature of the bandgap depends on the concentration of the adsorbate: for fluorination the direct bandgap first decreases, and then increases while becoming indirect, with increasing fluorination, while for oxidation the bandgap first increases and then decreases, while mostly maintaining its direct nature. Further we find that the unique anisotropic free-carrier effective mass for both the electrons and holes, can be changed and even rotated by 90 degrees, with controlled chemisorption, which can be useful for exploring unusual quantum Hall effect, and novel electronic devices based on phosphorene.
We present a double-resonant Raman mode in few-layer graphene, which is able to probe the number of graphene layers reliably. This so-called N mode on the low-frequency side of the G mode results from a double-resonant Stokes/anti-Stokes process combining a LO and a ZO phonon. Simulations of the double-resonant Raman spectra in bilayer graphene show very good agreement with the experiments. The investigation of the out-of-plane ZO phonon for layer number determination is expected to be transferable to other layered materials like boron nitride.
Two-dimensional (2D) transition metal dichalcogenides (TMDCs) have been the subject of sustained research interest due to their extraordinary electronic and optical properties. They also exhibit a wide range of structural phases because of the different orientations that the atoms can have within a single layer, or due to the ways that different layers can stack. Here we report the first study of direct-visualization of structural transformations in atomically-thin layers under highly non-equilibrium thermodynamic conditions. We probe these transformations at the atomic scale using real-time, aberration corrected scanning transmission electron microscopy and observe strong dependence of the resulting structures and phases on both heating rate and temperature. A fast heating rate (25 C/sec) yields highly ordered crystalline hexagonal islands of sizes of less than 20 nm which are composed of a mixture of 2H and 3R phases. However, a slow heating rate (25 C/min) yields nanocrystalline and sub-stoichiometric amorphous regions. These differences are explained by different rates of sulfur evaporation and redeposition. The use of non-equilibrium heating rates to achieve highly crystalline and quantum-confined features from 2D atomic layers present a new route to synthesize atomically-thin, laterally confined nanostrucutres and opens new avenues for investigating fundamental electronic phenomena in confined dimensions.
Structural, electronic and magnetic properties of bulk ilmenite CoTiO$_3$ are analyzed in the framework of Density Functional Theory (DFT), using the Generalized Gradient Approximation (GGA) and Hubbard-corrected approaches. We find that the G-type antiferromagnetic (G-AFM) structure, which consists of antiferromagnetically coupled ferromagnetic $ab$ planes, is the ground-state of the system, in agreement with experiments. Furthermore, cobalt titanates present two critical temperatures related to the breaking of the inter- and intra-layer magnetic ordering. This would result in the individual planes remaining ferromagnetic even at temperatures above the Neel temperature. When spin-orbit coupling is included in our calculations, we find an out-of-plane magnetic anisotropy, which can be converted to an in-plane anisotropy with a small doping of electrons corresponding to about 2.5% Ti substitution for Co, consistent with experimental expectations. We thus present a disorder-dependent study of the magnetic anisotropy in bulk $text{CoTiO}_3$, which will determine its magnon properties, including topological aspects.
Phosphorene is a new two-dimensional material composed of a single or few atomic layers of black phosphorus. Phosphorene has both an intrinsic tunable direct band gap and high carrier mobility values, which make it suitable for a large variety of optical and electronic devices. However, the synthesis of single-layer phosphorene is a major challenge. The standard procedure to obtain phosphorene is by exfoliation. More recently, the epitaxial growth of single-layer phosphorene on Au(111) has been investigated by molecular beam epitaxy and the obtained structure has been described as a blue-phosphorene sheet. In the present study, large areas of high-quality monolayer phosphorene, with a band gap value at least equal to 0.8 eV, have been synthesized on Au(111). Our experimental investigations, coupled with DFT calculations, give evidence of two distinct phases of blue phosphorene on Au(111), instead of one as previously reported, and their atomic structures have been determined.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
