Adsorption and One-Dimensional Growth of Al and in Chains on Si(100): 2×1: A Kinetic Monte Carlo Approach

Understanding the adsorption of adatom on the surface of an adsorbent and its interaction with defect sites should be considered in tailoring the growth of one-dimensional (1D) chains. Kinetic Monte Carlo simulation of a suitable atomistic lattice-gas model describing the adsorption and 1D submonolayer growth of Al and In on Si(100): 2 × 1 was performed to investigate the resulting nanowire morphology in the presence of various C-defect densities at various deposition temperatures. Average island density (N av ) in Al/Si (100) generally obeys the classically predicted Arrhenius behaviour as temperature increases. By contrast, In adatoms exclusively nucleate on C defect, where N av is equivalent to defect density. In Al/Si (100) and In/Si (100), N av showed linear and ‘power law’ dependence on coverage, respectively, whereas the average island size (S av ) for both systems showed linear dependence on coverage. The nanowires morphology in the Al/Si (100) system showed considerable dependence on flux variation. Because of the low-diffusion barrier of In adatom and high-detachment barrier on C defect, In/Si (100) is insensitive to flux. Morphology of In chains is dictated by the defect density: an increase in defect density caused higher island density and smaller island sizes irrespective of coverage and flux rates

Prediction of Quantum Anomalous Hall Effect in MBi and MSb (M:Ti, Zr, and Hf) Honeycombs

Abstract The abounding possibilities of discovering novel materials has driven enhanced research effort in the field of materials physics. Only recently, the quantum anomalous hall effect (QAHE) was realized in magnetic topological insulators (TIs) albeit existing at extremely low temperatures. Here, we predict that MPn (M =Ti, Zr, and Hf; Pn =Sb and Bi) honeycombs are capable of possessing QAH insulating phases based on first-principles electronic structure calculations. We found that HfBi, HfSb, TiBi, and TiSb honeycomb systems possess QAHE with the largest band gap of 15 meV under the effect of tensile strain. In low-buckled HfBi honeycomb, we demonstrated the change of Chern number with increasing lattice constant. The band crossings occurred at low symmetry points. We also found that by varying the buckling distance we can induce a phase transition such that the band crossing between two Hf d-orbitals occurs along high-symmetry point K2. Moreover, edge states are demonstrated in buckled HfBi zigzag nanoribbons. This study contributes additional novel materials to the current pool of predicted QAH insulators which have promising applications in spintronics