Electronic and mechanical properties of wurtzite type SiC nanowires

Abstract

One-dimensional nanomaterials have attracted considerable attention due to their potential use in nanotechnology. To date various types of nanostructures have been synthesized by a number of experimental techniques. Silicon carbide (SiC) based nanoscale materials are currently attracting great interest since SiC is a promising material for next generation of electronic devices. SiC is expected to have some advantages over silicon based nanostructures because of its outstanding physical properties, such as excellent chemical stability, a wide band gap, high stiffness, high hardness, high thermal conductivity and a high melting point.Recent experiments have revealed a variety of SiC based nanoscale materials. Sun et al. have produced SiC nanotubes and nanowires with various shapes and structures through the reaction of silicon with multiwalled carbon nanotubes at different temperatures [1]. SiC nanowires with 10 to 30 nm diameters have been grown by chemical vapor deposition technique [2,3]. Using an iron particle as a catalyzer, Zhou et al. [4] manage to reduce the SiC wire size to 5 nm. SiC nanowires also have been synthesized by arcdischarge [5,6] and by direct chemical reaction [7]. However, little is known about the atomic structures and physical properties of these SiC nanowires. Recently, Rurali [8] has shown that a pure SiC nanowire grown along the [100] direction with a bulk zinc-blende core is metallic due to the presence of surface states, but hydrogen terminated wires exhibit quantum confinement effect, i.e., a broadening of band gap energy. Quantum confinement effect has also been demonstrated in other nanoscale SiC systems [9,10]. However, SiC quantum dots obtained by etching hexagonal SiC (6H-SiC) have yielded contradictory results on quantum confinement effects [11,12]. The observation of the quantum effects makes SiC nanostructures an even more interesting system because it suggests a possibility of designing SiC based materials with blue or higher frequency emission, e.g., UV.A wurtzite type SiC nanorod with an average diameter of 20 nm and a length of 100 nm has been obtained by pulsed laser ablation on 6H-SiC near 1200 °C [13]. Based on the known stability of the unreconstructed (1010) surface of the wurtzite structure [14], one expects that wurtzite type SiC nanorods (W-SiCNRs) or nanowires (W-SiCNWs) might show remarkable stability. However, a detailed understanding of the structure of thin W-SiCNRs and W-SiCNWs and of their electronic and mechanical properties is required for their future developments and applications in nanotechnology. In this Letter, we carry out ab initio calculations to explore the one-dimensional behavior of pure and hydrogen passivated SiC nanowires grown along [0001] direction of the wurtzite structure. Such an investigation is also helpful in understanding the stability and physical properties of other hexagonal-type (4H and 6H) SiC nanowires/nanorods.The calculations were performed with the SIESTA code [15], which implements density functional theory (DFT) with the p...

Electronic properties of alkali- and alkaline-earth-intercalated silicon nanowires

“…The smallest of the clathrate-type nanowires are based on the Si 20 and Si 24 cages 3,8 and have been predicted to be the most stable configurations in some experiments 3 . These nanowires are expected to show many of the clathrate properties due to their similarities with the bulk phases.…”

“…However, pure silicon nanowires derived from the silicon clathrate phases do not need any impurity to be stabilized and are expected to be the most stable for very small diameters 3,20 . These nanowires can have many different shapes 8,9,20,21 depending on the basic unit of repetition and the growth direction.…”

Mechanical and electronic properties of SiC nanowires: An ab initio study

“…Our results for 3Cand 2H-SiCNWs are consistent with previous theoretical works. [20][21][22] In addition, we have investigated the effects of strain on the electronic properties of SiCNWs. All nanowires were strained from -4% (compressive) to +4% (tensile) strain, with increments of 1%.…”

“…Rurali 18 investigated (using first-principles calculations) the electronic properties of pure and hydrogen-passivated 3C-SiCNWs 19 grown along the [110] direction, and showed that pure NWs present metallic character due to surface a) Electronic mail: jmmorbec@gmail.com reconstructions, whereas quantum confinement induces a gap-broadening effect in hidrogenated NWs. In another theoretical work, Durandurdu 20 observed that the band gaps of pure wurtzite SiCNWs increase with increasing diameters, in contrast to hydrogenated wurtzite SiCNWs whose band gaps decrease with increasing diameters. Using first-principles calculations, Yan et al 21 investigated the effect of uniaxial stress on the electronic properties of hydrogen-passivated [111] 3C-SiCNWs.…”

An ab initio study of cluster-assembled hydrogenated silicon nanotubes

“…(3) Polycrystalline forms of nanowires [14], (4) Metal encapsulated polygonal prism nanotubes [15][16][17][18][19][20], (5) Carbon nanotube like structures [21][22][23][24][25][26][27], (6) Fullerene-based structures [28,29], (7) Metal centered fullerene-based structures [30], (8) Hydrogenated single-wall silicon CNT like nanotubes [31][32][33], (9) Exohydrogenated fullerene-like structures [34,35], (10) Multiwall nanotubes [36][37][38].…”