Spin-dependent photogalvanic (PG) effect in low-dimensional spin semiconductors has been attracted great interesting recently. Here, we have studied the spin semiconducting feature and spin-dependent photocurrent in the two-dimensional (2D) silicene...
We propose a novel two-dimensional (2D) lateral superlattice based on silicene alternately saturated by hydrogen and halogen atoms, named as hydrogenated-silicene/halogenated-silicene superlattices (SHSXSLs, X = F, Cl, Br, and I). Employing ab initio electronic calculations, we systematically investigate the structural, electronic, and optical properties of SHSXSLs. Our results show that these superlattices are much stable than silicene as saturating the dangling bonds and the bandgap and carrier effective mass of superlattices can be modulated by the width of components due to the confinement and interfacial effects. By calculating the band alignment, it is found that all superlattices exhibit the type I alignment. Specifically, SHSCl,BrSLs have very small valence band offset and large conduction band offset, which can separate electrons and holes in these systems. Furthermore, the band edge positions of SHSCl,BrSLs satisfy the redox potential of the water splitting and SHSCl,BrSLs exhibit strong absorption in the visible region, suggesting that these superlattices are promising materials for photovoltaics and photocatalytics. This new type of superlattice structure can be applied to other 2D materials with strong activity to enhance the stability and modulate the properties effectively.
The spin photocurrent of defective‐silicane‐based photoelectric devices is studied using non‐equilibrium Green's function with first‐principles density functional theory. The calculations reveal that the silicane with H vacancies is a ferromagnetic (FM) semiconductor with a 0.27 μB magnetic moment on the unhydrogenated Si atom. Due to the unique electronic structure, the directions and spin polarizations of the spin photocurrents can be effectively tuned by the polarization/phase angles or the photon energy (Eph) of the incident illumination. Especially, the 100% spin‐polarized photocurrents can be induced, as the Eph is 1.2–2.2 eV for both linearly polarized light (LPL) or circularly polarized light (CPL). Furthermore, the pure spin currents can be obtained by the CPL, as the Eph is 2.6 eV. These results indicate that defective silicane is a promising spintronic material.
Intercalation of hydrogen is important for understanding the decoupling of graphene from SiC(0001) substrate. Employing first-principles calculations, we have systematically studied the decoupling of graphene from SiC surface by H atoms intercalation from graphene boundary. It is found the passivation of H atoms on both graphene edge and SiC substrate is the key factor of the decoupling process. Passivation of graphene edge can weaken the interaction between graphene boundary and the substrate, which reduced the energy barrier significantly for H diffusion into the graphene-SiC interface. As more and more H atoms diffuse into the interface and saturate the Si dangling bonds around the boundary, graphene will detach from substrate. Furthermore, the energy barriers in these processes are relatively low, indicating that these processes can occur under the experimental temperature.
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