Fe, Co and Ni Adatoms Adsorbed on Silicene: A DFT Study

Two-dimensional materials have attracted much research attention given their intriguing properties. The latest member of this class of materials is silicene. In this work, we investigate the adsorption of Fe, Co and Ni adatoms on silicene using plane-wave density functional theory calculations within the Perdew-Burke-Ernzerhof parameterization of the generalized gradient approximation for the exchange-correlation potential. In particular, we calculate the binding energy, magnetization, and projected electronic configurations of these adatoms adsorbed at different sites on the silicene. Our calculations show that the hole site (i.e. in the centre of a hexagonal-like arrangement of Si atoms) is the most stable configuration for all three elements. The Fe, Co and Ni adatoms were found to bind very strongly to the silicene, between 4-6 times stronger compared to their binding strength when adsorbed on graphene. Like graphene, wefindthat the Ni adatom binds strongest. We alsofindthat the binding strength is inversely proportional to the distance between the metal adatom and a Si atom in the silicene sheet. Our work suggests that these adatoms are stable on silicene and have potential to be used in applications such as spintronics and topological insulators

Band-offsets scaling of low-index Ge/native-oxide heterostructures

Abstract We investigate, through XPS and AFM, the pseudo layer-by-layer growth of Ge native oxide across Ge(001), (110) and (111) surfaces in ambient environment. More significantly, our study reveals a universal set of valence and conduction band offset (VBO and CBO) values observed for Ge(001), Ge(110), and Ge(111) surfaces as a function of Ge-oxide concentration. We find that the band offsets appear to be the same across these low-index Ge surfaces i.e., for Ge-oxide/Ge heterostructures with the same Ge-oxide overlayer concentration or thickness. In contrast, different oxidation rates for Ge(001), Ge(110), and Ge(111) surfaces were observed, where the oxidation rate is fastest for Ge(001), compared to Ge(110) and Ge(111). This can be attributed to the different number of unsatisfied Ge dangling bonds (2 vs 1) associated to the respective ideal Ge surface in forming Ge-oxide. Thus, at any given oxidation time, the oxide concentration or thickness for each type of low index Ge surface will be different. This in turn will lead to different band offset value observed for each type of Ge surface. More significantly, we show that while oxidation rates can differ from different Ge surface-types, the band offset values can be estimated simply based on the Ge-oxide concentration regardless of Ge surface type

Effect of orbital and ionic dynamics coupling in barrier crossing rates for Car-Parrinello molecular dynamics

Chemical Physics Letters621146-15

Infrared spectroscopic ellipsometry study of sulfur-doped In0.53Ga0.47As ultra-shallow junctions

Sulfur mono-layer doped In0.53Ga0.47As films were investigated by infrared spectroscopic ellipsometry. The complex dielectric function of doped layers shows free carrier response which can be described by a single Drude oscillator. Electrical resistivities, carrier relaxation times, and active carrier depths are obtained for the shallow n-In0.53Ga0.47As films. Our results indicate that sub-10 nm sulfur-doped layers with active carrier concentration as high as 1.7 × 1019 cm−3 were achieved. Sheet resistances estimated from infrared spectroscopic ellipsometry are in good agreement with those obtained by electrical methods.Published versio

X-ray-induced Cu deposition and patterning on insulators at room temperature

X-ray irradiation is shown to trigger the deposition of Cu from solution, at room temperature, on a wide variety of insulating substrates: glass, passivated Si, TiN/Ti/SiO2/Si and photoresists like PMMA and SU-8. The process is suitable for patterning and the products can be used as seeds for electroplating of thicker overlayers.11Nsciescopu

Architecturing Covalently Bonded Organic Bilayers on the Si(111)-(7 × 7) Surface via in Situ Photoinduced Reaction

Controlled formation of covalently bonded <i>N</i>-benzylideneaniline-like molecular layers has been achieved by photoinduced reaction of benzonitrile molecules physisorbed on the 4-bromostyrene modified Si(111)-(7 × 7) surface. The photoinduced reaction results in the C–Br bond cleavage and produces a radical site which concurrently reacts with the CN cyano group of the physisorbed benzonitrile molecule above to form the −C–NC– covalent linkage. X-ray photoelectron spectroscopy (XPS) and high-resolution electron energy loss spctroscopy (HREELS) experiments together with density functional theory (DFT) calculations confirm the formation of covalently bonded <i>N</i>-benzylideneaniline-like molecular layers on the silicon surface. The formation of this secondary molecular layer by photoinduced reaction may provide a direct pathway for further organic synthesis and fabrication of organic multilayers on semiconductor surfaces in a well-controlled enviornment

Detrimental effects of oxygen vacancies in electrochromic molybdenum oxide

10.1021/acs.jpcc.5b02609Journal of Physical Chemistry C1191910592-1060