First-principles investigation of pentagonal and hexagonal core-shell silicon nanowires with various core compositions

Abstract

Properties of various core-shell silicon nanowires are investigated by extensive first-principles calculations on the geometric optimization as well as electronic band structures of the nanowires by using pseudopotential plane-wave method based on the density-functional theory. We show that different geometrical structures of silicon nanowires with various core compositions, formed by stacking of atomic polygons with pentagonal or hexagonal cross sections perpendicular to the wire axis, can be stabilized by doping with various types of semiconductor ͑Si, Ge͒, nonmetal ͑C͒, simple metal ͑Al͒, and transition metal ͑TM͒, 3d ͑Ti, Cr, Fe, Co, Ni, Cu͒, 4d ͑Nb, Mo, Pd, Ag͒, and 5d ͑Ta, W, Pt, Au͒, core atoms. Dopant atoms are fastened to a linear chain perpendicular to the planes of Si-shell atoms and are located through the center of planes. According to the stability and energetics analysis of core-shell Si nanowires, the eclipsed pentagonal and hexagonal structures are energetically more stable than the staggered ones. Electronic band structure calculations show that the pentagonal and hexagonal Si-shell nanowires doped with various different types of core atoms exhibit metallic behavior. Magnetic ground state is checked by means of spin-polarized calculations for all of the wire structures. The eclipsed hexagonal structure of Si-shell nanowire doped with Fe atom at the core has highest local magnetic moment among the magnetic wire structures. Electronic properties based on band structures of Si-shell nanowires with different dopant elements are discussed to provide guidance to experimental efforts for silicon-based spintronic devices and other nanoelectronic applications.

Structural Evolution and Electronic Properties of TaSin–/0 (n = 2–15) Clusters: Size-Selected Anion Photoelectron Spectroscopy and Theoretical Calculations

“…23 TaSi n (n = 1−3, 12) clusters supported on the graphene surfaces were also investigated using the PBE functional with the projected augmented wave (PAW) pseudopotentials. 24 The formation of hydrogenated and dehydrogenated TaSi n + (n = 1−13) clusters in an ion trap and mass analyses of their relative abundances suggested TaSi 13 + to be the smallest size forming Ta-endohedral Si n cagelike structures, 25 which was further confirmed by the subsequent adsorption reactivity toward H 2 O vapor experi-ments of TaSi n + (n = 6−20) clusters. 26 The photoelectron spectra of TaSi n − anions in the size range of n = 6−17 were measured at 213 nm wavelength.…”

“…Transition-metal (TM) atom doped silicon clusters can form stable fullerene-like structures − and also can exhibit novel electronic properties. − They may be used as potential building blocks for producing novel silicon-based nanomaterials. − Ta–Si clusters have received great attention because tantalum is widely used in alloys and nanomaterials. It has been found that Ta–Si film can be used for manufacturing capacitors and resistors with excellent thermal stability. − TaSi x nanostructure film can be used as a barrier material for Cu metallization, and silicide TaSi 2 film can be used as Schottky barriers and ohmic contacts with high-temperature mechanical strength and oxidation resistance .…”

Structures, magnetic properties, and electronic counting rule of metals‐encapsulated cage‐like M2 Si18 (M = Ti‐Zn) clusters

“…Kumar and Kawazoe8 also gave the double HP structure and its isomer with one of the outer hexagons in the antiprism for M 2 Si 18 . Recently, Berkdemir and Gulseren28 performed a first‐principle investigation for pentagonal and hexagonal core‐shell silicon nanowires doping with 3 d TM. In this article, we provide our first‐principle structural and electronic investigation for double 3 d TM atoms doped silicon M 2 Si 18 (M = Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) clusters, based on these researches.…”

Unveiling the pentagonal nature of perfectly aligned single-and double-strand Si nano-ribbons on Ag(110)

“…Despite the large effort devoted to design Si-based structures analogous to those of carbon, the existence of Si pentagonal rings has only been reported in clathrate bulk phases 2 or in complex Si reconstructions 3 4 . Several theoretical studies have hypothesized stable Si pentagonal structures either in the form of one-dimensional (1D) nanotubes 5 6 or at the reconstructed edges of silicene nano-ribbons (NRs) 7 8 or even as hydrogenated penta-silicene 9 or highly corrugated fivefold coordinated siliconeet 10 2D sheets, the latter recognized as a topological insulator 11 . However, to date none of them have yet been synthesized.…”