M. Luo

Synthesis and optical properties of ultralong ZnO microbushes

Ultralong ZnO microbushes have been synthesized using a simple thermal evaporation and condensation method by Cu catalysts. The lengths of the ZnO microbushes range from several millimeters to more than one centimeter and the diameters of the branches’ teeth are about 300 nm. The growth mechanism of the ultralong microbushes and the catalytic behavior of the copper are discussed. Room-temperature photoluminescence spectra of the ultralong ZnO microbushes showed a UV emission band at about 388 nm and wide green emissions at around 525 nm. It may be very attractive for commercial applications such as electrical devices, microelectromechanical systems and sensors.

Modulation of band gap by normal strain and an applied electric field in SiC-based heterostructures

The structure and electronic properties of the WS2/SiC van der Waals (vdW) heterostructures under the influence of normal strain and an external electric field have been investigated by the ab initio method. Our results reveal that the compressive strain has much influence on the band gap of the vdW heterostructures and the band gap monotonically increases from 1.330 to 1.629 eV. The results also imply that electrons are likely to transfer from WS2 to SiC monolayer due to the deeper potential of SiC monolayer. Interestingly, by applying a vertical external electric field, the results present a parabola-like relationship between the band gap and the strength. As the E-field changes from to −0.50 +0.20 V/Å, the band gap first increases from zero to a maximum of about 1.90 eV and then decreases to zero. The significant variations of band gap are owing to different states of W, S, Si, and C atoms in conduction band and valence band. The predicted electric field tunable band gap of the WS2/SiC vdW heterostructures is very promising for its potential use in nanodevices.

Ab initio study on nonmetal and nonmagnetic metal atoms doped arsenene

The structural, electronic, and magnetic properties of arsenene doped with a series of nonmetals (B, C, F, N, and O) and nonmagnetic metals (Al, Ga, Li, Mg, and Na) are investigated using density functional theory. Magnetism is observed in the case of C. Among all the cases, the C-doped system is the most stable formed system. Hence, we study the ferromagnetic interaction in two-C-doped arsenene. Interestingly, both nonmagnetic (NM) and antiferromagnetic (AFM) states have been observed. As the increasing C−C distance, the magnetic coupling between the moments induced by two C is found to be AFM and the origin of the coupling can be attributed to the p−p hybridization interaction involving polarized electrons.

Synthesis and Growth Mechanism of Ultra-long ZnO Nanocombs and Nanobelts on Cu Substrate

We successfully synthesized ultralong ZnO nanocombs and nanobelts on Cu substrate for the first time. The morphology and structure of the as-grown ZnO nanocombs and nanobelts were characterized by means of scanning electron microscopy and X-ray diffraction. Scanning electron microscopy images show that Cu substrate is red and not oxidized, X-ray diffraction studies support Cu is present during the growth process, and we explained the growth mechanism for ultralong ZnO nanostructures.

Band gap tuning of Ge/SiC bilayers under an electric field: a density functional study

The structure and electronic properties of Ge/SiC van der Waals (vdW) bilayer under the influence of an electric field have been investigated by the first-principles method. Without an electric field, the system shows a small band gap of 126 meV at the equilibrium state. Interestingly, by applying a vertical external electric field, the results present a parabola-like relationship between the band gap and the strength. As the negative E-field changes from 0.0 to −0.40 V/Å, the band gap first increases to a maximum of about 378 meV and then decreases to zero. A similar trend is exhibited for the positive E-field, ranging from 0.0 to +0.40 V/Å. The band gap reaches a maximum of about 315 meV at +0.10 V/Å. The significant variations of band gap are owing to different states of Ge, Si, and C atoms in conduction band and valence band. The predicted electric field tunable band gap of the Ge/SiC vdW heterostructures is very promising for its potential use in nanodevices.

Tunable magnetic interaction by an applied electric field in a Co-adsorbed SiC monolayer

The magnetic properties of Co-adsorbed SiC monolayer under an external electric field are investigated using first-principles method. In the absence of the electric field, the interaction between two Co atoms is ferromagnetic, which is originated by the p−d hybridization between Co and its neighboring C and Si atoms. When an electric field was introduced along the c axis, the interaction between two Co dopants switched from ferromagnetic to antiferromagnetic, which could be dominated by the competition between p−d exchange and superexchange. Moreover, the magnetic anisotropy prefers to parallel to the a axis and it seems not to be turn into the c axis under the electric field.