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In this work, we have constructed the hydrogenated hexagonal boron nitride (h-BN) by placing hydrogen atom at different surface sites. The possibility of hydrogen adsorption on the BN surface has been estimated by calculating the adsorption energy. The electronic properties were calculated for different hydrogenated BNs. The theoretical calculation was based on the Density Functional Theory (DFT). The electron-exchange energy was treated within the most conventional functional called generalized gradient approximation. The calculated band gap of pure BN is 3.80 eV. The adsorption of two H-atoms at two symmetrical sites of B and N sites reduces the band gap value to 3.5 eV. However, in all other combination the systems show dispersed band at the Fermi level exhibiting conducting behavior. Moreover, from the analysis of band structure and Density Of States we can conclude that, the hydrogenation tunes the band gap of hexagonal boron nitride.

International audience; We report the electronic and magnetic properties along with the Curie temperature (TC) of the inverse full Heusler alloy (HA) Fe2CoAl obtained by using the first-principles computational method. Our calculations suggests that Fe2CoAl is a magnetic metal when treated within PBE-GGA under the applied compressive pressures. However, the implementation of electron–electron (U) (i.e., GGA+U) with varying compressive pressure (P) drastically changes the profile of the electronic structure. The application of GGA+U along with pressure induces ferromagnetic half-metallicity with an integer value of total magnetic moment ∼4.0 μB per unit cell. The integer value is in accordance with the Slater–Pauling's rule. Here, we demonstrate the variation of semiconducting gap in the spin down channel. The band gap increases from 0.0 eV to 0.72 eV when increasing the pressure from 0 to 30 GPa. Beyond 30 GPa, the electronic band gap decreases, and it is completely diminished at 60 GPa, exhibiting metallic behaviour. The analysis of the computed results shows that the treatment of electron–electron interactions within GGA+U and the application of compressive pressure in Fe2CoAl enables d–d orbital hybridization giving rise to a half-metal ferromagnet. The TC calculated from mean field approximation (MFA) decreases up to 30 GPa and then increases linearly up to 60 GPa.

We report the electronic and magnetic properties along with the Curie temperature (

Ab initio calculations showing strain induced bandgap variation in 2D graphene like structure of CdO monolayer is presented in this work. The density functional theory (DFT) calculations were performed using pseudopotential and numerical nano orbitals basis set as implemented in SIESTA. The electron exchange correlation is treated within the local density approximation (CA-LDA). KS-orbitals were expanded based on the double zeta polarization (DZP) with mesh cutoff 250 Ry. The first Brillouin zone was integrated by using 8 x 8 x 1 k-mesh within Monkhorst pack scheme. The optimized lattice parameter was found to be 3.66 □, which is comparable with reported data. Within the compressive strain limit chosen in this work (- 8%), the bandgap remains direct. In the tensile strain, transition from direct to indirect bandgap is observed at 5 % and when the bond length is stretched further, metallic like behavior is observed at 14%, beyond which the conduction band minima falls below the Fermi level. The nature of variation of effective masses of electrons, heavy holes and light holes are calculated from energy bands close to the gamma point, where the band lines are parabolic. While the electrons and light holes effective masses remain almost constant in the range of our calculations, the heavy holes effective masses significantly decreased in the compressive strain and in the tensile strain it significantly increases from its value at the relaxed lattice. Our theoretical predictions in this work will provide valuable information for fabrication of CdO monolayer in nano-electromechanical systems (NEMS) and nano-optomechanical systems (NOMS) devices.

Two dimensional carbon nanostructures (carbon nanosheets) are fabricated using Hot Wire Chemical Vapor Deposition (HWCVD) technique assisted by H radical injection, using CH 4 as source gas. Carbon nanosheets are grown on crystalline Si(100) wafer as well as on corning glass substrat e without using catalyst. The grown carbon nanosheets are aligned vertically on the substrate with thickness in the range of 10-20 nm and about 60-80 nm in height. Carbon nanosheets, HWCVD 1. INTRODUCTION Two dimensional carbon nanostructures (carbon nanosheets) ha ve a wall structure which consist of graphene. It has sp 2 bonded carbon atoms in a honeycomb network. The graphene crystal lattice is considered to be the basic building block of other importa nt allotropes of carbon materials such as graphite (3D), nanotube (1D), and fullerenes (0D). From the application point of view, some of the most interesting properties of graphene are: very high carrier mobility up to ~25000cm 2 V -1 s -1 [1] and high thermal conductivity in the range of 3080-5150 W/m-K [2] at room temperature. The elastic modulus and the intrinsic strength of defect free monolayer graphene sheets are measured to be 1.0 TPa and 130 GPa, respectively [3]. The enhancement in current and heat conduction properties are beneficial for electronic, interconnect and thermal application of graphene. It has also been demonstrated that graphene devices can operate at very low-levels of the electronics flicker noise, which is important for the application in sensors and communications [4]. A number of methods have been used for the synthesis of graphene sheets. Graphene sheets have been prepared using mechanical [5] and chemical exfoliation [6] of bulk graphite, thermal decomposition of carbon terminated from SiC [7] and Chemical Vapor Deposition (CVD) technique using CH

Nanocrystalline cubic silicon carbide (nc-3C-SiC) films are deposited using hot wire chemical vapour deposition technique at ~350 °C on glass substrates using SiH4 /CH4/H2 as precursor gases. We investigated the influence of total gas pressure on the structural, optical and transport properties of nc-3C-SiC films. Raman scattering spectra and X-ray diffraction patterns revealed that the film prepared below 2 mbar is nanocrustalline silicon (nc-Si), while at ≥ 2 mbar films are nc-3C-SiC. We achieved high deposition rate (≥ 14-20 nm/min), high optical band gap (3.2-3.4 eV) and high conductivity (~ 10-4 -10-2 Ω-1cm-1) suitable for window layer for Solar cells.