Abstract: In this work, the carbon (C) and silicon (Si) doping and codoping effects on beta-arsenene (As) monolayer structural, electronic, and magnetic properties have been comprehensively investigated using first-principles calculations. The studied two-dimensional (2D) materials exhibit good stability. Pristine beta-As single layer is an indirect gap semiconductor with a band gap of 1.867(2.441) eV as determined by PBE(HSE06) functional. Due to the difference in atomic size and electronic interactions, C and Si substitution induces a significant local structural distortion. Depending upon dopant concentration and doping sites, feature-rich electronic properties including non-magnetic semiconductor, magnetic semiconductor and half-metallicity may be obtained, which result from p-p interactions. High spin-polarization at the Fermi level vicinity and significant magnetism suggest As:1C, As:2C, As:1Si, As:2Si, and As:CSi systems as prospective spintronic 2D materials. While, the C-C, Si-Si, and C-Si dimer doping decreases electronic band gap, making the layer more suitable for applications in optoelectronic devices. Results presented herein may suggest an efficient approach to create novel multi-functional 2D materials from beta-As monolayer.

Abstract: Hexagonal boron nitride nanowall thin films were deposited on Si(100) substrates using a Ar(51%)/N-2(44%)/H-2(5%) gas mixture by unbalanced radio frequency sputtering. The effects of various target-to-substrate distances, substrate temperatures, and substrate tilting angles were investigated. When the substrate is close to the target, hydrogen etching plays a significant role in the film growth, while the effect is negligible for films deposited at a farther distance. The relative quantity of defects was measured by a non-destructive infrared spectroscopy technique that characterized the hydrogen incorporation at dangling nitrogen bonds at defect sites in the deposited films. Despite the films deposited at different substrate tilting angles, the nanowalls of those films were found to consistently grow vertical to the substrate surface, independent of the tilting angle. This implies that chemical processes, rather than physical ones, govern the growth of the nanowalls. The results also reveal that the degree of nanowall crystallization is tunable by varying the growth parameters. Finally, evidence of hydrogen desorption during vacuum annealing is given based on measurements of infrared stretching (E-1u) and bending (A(2u)) modes of the optical phonons, and the H-N vibration mode.