We develop a nucleation-based model to explain the formation of wurtzite phase during catalyzed growth freestanding nanowires zinc blende semiconductors. show that in vapor-liquid-solid nanowire growth, nucleation generally occurs preferentially at triple line. This entails major differences between and nuclei. Depending on pertinent interface energies, is favored high liquid supersaturation. explains our systematic observation early gold-catalyzed GaAs nanowires.

Theoretical model for the growth of semiconductor nanowires is developed, which enables one to determine conditions under formation possible. General expression nanowire rate as function its radius and obtained analyzed. The also describes transformation from cubic hexagonal crystal phase nanowires. It shown that observed structure controlled mainly by kinetics. Structural diagrams probabilities are calculated functions supersaturation within plausible range material parameters. Numerical...

GaAs nanowires were grown by molecular-beam epitaxy on (111)B oriented surfaces, after the deposition of Au nanoparticles. Different growth durations and different terminations tested. After nanowires, structure composition metallic particles analyzed transmission electron microscopy energy dispersive x-ray spectroscopy. We identified three compounds: hexagonal β′Au7Ga2 structure, orthorhombic AuGa an almost pure face centered cubic structure. explain how these solid phases are related to...

In semiconducting nanowires, both zinc blende and wurtzite1 crystal structures can coexist.2−4 The band structure difference between the two lead to charge confinement.5 Here we fabricate study single quantum dot devices6 defined solely by phase in a chemically homogeneous nanowire observe photon generation. More generally, our results show that this type of carrier confinement represents novel degree freedom device design at nanoscale.

We develop a quantitative model of the self-catalyzed vapor-liquid-solid growth GaAs nanowires, that depends on only few priori unknown physical parameters. The is based sole consideration As species and incorporates all relevant mechanisms exchange between vapor, liquid, solid phases, namely direct impingement molecules droplet, their re-emission by neighboring surfaces, evaporation from nucleation at solid-liquid interface. It reproduces quantitatively salient features our experimental...

A theoretical model of nanowire formation by the vapor-liquid-solid mechanism during molecular beam epitaxy and related growth techniques is presented. The unifies conventional adsorption-induced model, diffusion-induced nucleation-mediated on liquid-solid interface. concentration deposit atoms in liquid alloy, diameter, all other characteristics process are treated dynamically as functions time. provides length-diameter dependences nanowires dependence length technologically controlled...

Crystal growth often proceeds by atomic step flow. When the surface area available for is limited, nucleation and progression of steps can be affected. This issue particularly relevant to formation nanocrystals. We examine case Au-catalyzed GaAs nanowires, which we grow in a transmission electron microscope. Our situ observations show that layers nucleate at periphery interface between nanowire catalyst droplet. From this starting location, flows within restricted hexagonal shape. At...

Self-catalyzed growth of GaAs nanowires by molecular beam epitaxy on (111)Si substrates is investigated introducing AlxGa1–xAs time markers. The nanowire elongation rate found to be radius-independent, constant at substrate temperatures below 650 °C and linearly increasing with the incoming arsenic flux. basic question which pathways are followed species contributing clarified. flow As atoms directly impinging Ga catalyst drop significantly smaller than consumption growth. Thus,...

We report on the new mode of vapor−liquid−solid nanowire growth with a droplet wetting sidewalls and surrounding rather than resting its top. It is shown theoretically that such an unusual configuration happens when catalyzed by lower surface energy metal. A model nonspherical elongated shape in case developed. Theoretical predictions are compared to experimental data Ga-catalyzed GaAs nanowires molecular beam epitaxy. In particular, it demonstrated experimentally observed indeed...

Epitaxial growth of GaN nanowires on graphene is demonstrated using molecular beam epitaxy without any catalyst or intermediate layer. Growth highly selective with respect to silica which the flakes, grown by chemical vapor deposition, are transferred. The grow vertically along their c-axis and we observe a unique epitaxial relationship ⟨21̅1̅0⟩ directions wurtzite lattice parallel carbon zigzag chains. Remarkably, nanowire density height decrease increasing number layers underneath. We...

Crystal phase switching between the zincblende and wurtzite structures in III-V nanowires is crucial from fundamental viewpoint as well for electronic photonic applications of crystal heterostructures. Here, results situ monitoring self-catalyzed vapor-liquid-solid growth GaAs by molecular beam epitaxy inside a transmission electron microscope are presented. It demonstrated that occurrence or determined sole parameter, droplet contact angle, which can be finely tuned changing group III V...

The Au-assisted molecular beam epitaxial growth of InAs nanowires is discussed. In situ reflection high-energy electron diffraction observations phase transitions the catalyst particles indicate that they can be liquid below eutectic point Au-In alloy. temperature range where covers we observed nanowire formation (380–430 °C). variation rate with investigated. Pure axial at high while mixed axial/lateral occurs low temperature. change shape duration studied. It shown significant lateral...

We report on the fabrication by Au-assisted molecular beam epitaxy of InP nanowires with embedded InAsP insertions. The growth temperature affects nucleation nanowire lateral surface. It is therefore possible to grow wires in two steps: fabricate an axial heterostructure (at 420 °C), and then cover it a shell 390 °C). alloy composition could be varied between InAs0.35P0.65 InAs0.5P0.5 changing As P flux ratio. When present, segments show strong room-temperature photoluminescence peak...

Abstract We report on the growth properties of InAs, InP and GaAs nanowires (NWs) different lattice mismatched substrates, in particular, Si(111), during Au‐assisted molecular beam epitaxy (MBE). show that critical diameter for epitaxial dislocation‐free III–V NWs decreases as mismatch increases equals 24 nm InAs 39 44 GaAs(111)B, 110 Si(111). When diameters exceed these values, are dislocated or do not grow at all. The corresponding temperature domains NW extend from 320 °C to 340 330 360...

This paper reports on the growth, structural and optical properties of GaN free-stranding nanowires synthesized in catalyst-free mode Si(111) substrate by plasma-assisted molecular beam epitaxy. Cylindrical with a hexagonal cross-section defined planes diameters down to 20 nm were observed. The nanowire length increases as function their diameter, following Gibbs–Thomson expression. growth rate lateral direction was studied using thin AlN marker layers showing that over axial ratio can be...

We elaborate InP(1-xA)s(x) nanowires by vapor-liquid-solid growth, with small and short composition oscillations produced on purpose a constant time period. The lengths of these oscillations, measured in single wires transmission electron microscopy, give access to instantaneous growth rates their distribution reveals the nucleation statistics. find that statistics are strongly sub-Poissonian, which proves events anticorrelated time. This effect, specific nanovolumes, efficiently regulates...

Semiconductor nanowires offer additional properties and more flexibility for many potential applications. However the precise control of their growth is very challenging much complex than two-dimensional layers. Here, we present a method which provides detailed information on formation. The implemented with In(P,As) grown by Au-catalyzed molecular beam epitaxy. Controlled periodic modulations incident vapor phase are generated. Due to these modulations, show small short oscillations...

We study theoretically and experimentally nonlinear effects during the ``vapor-liquid-solid'' growth of semiconductor nanowires. Nonlinear equation considered contains kinetic coefficients from surface sidewall diffusion which can be either signs. predict four possible scenarios: (I) infinite growth; (II) decomposition; (III) averaging to a finite length; (IV) continuing such that nanowires small initial length decay longer grow infinitely. present experimental evidence nontrivial scenarios...

We report the Au catalyst-assisted synthesis of 20 μm long GaAs nanowires by vapor-liquid-solid hydride vapor phase epitaxy (HVPE) exhibiting a polytypism-free zincblende for record radii lower than 15 nm down to 5 nm. HVPE makes use GaCl gaseous growth precursors at high mass input which fast dechlorination usual process temperature 715 °C results in planar rate (standard 30-40 μm/h). When it comes nanowires, solidification higher 100 μm/h is observed. Nanowire only proceeds introduction...

The bottom-up fabrication of regular nanowire (NW) arrays on a masked substrate is technologically relevant, but the growth dynamic rather complex due to superposition severe shadowing effects that vary with array pitch, NW diameter, height, and duration. By inserting GaAsP marker layers at time interval during self-catalyzed GaP array, we are able retrieve precisely evolution diameter height single NW. We then propose simple numerical scheme which fully computes play in infinite NWs....

The growth of III-III-V axial heterostructures in nanowires via the vapor-liquid-solid method is deemed to be unfavorable because high solubility group III elements catalyst droplet. In this work, we study formation by molecular beam epitaxy self-catalyzed GaAs with AlxGa1-xAs insertions. composition profiles are extracted and analyzed monolayer resolution using high-angle annular dark-field scanning transmission electron microscopy. We test successfully several procedures sharpen...

The band-gap (Egp) and valence band offset (ΔEv) energies of pseudomorphic GaAsSb layers on GaAs substrate are determined from temperature-dependent photoluminescence measurements GaAsSb/GaAs GaAsSb/GaAlAs quantum wells grown by molecular beam epitaxy. A clear evidence staggered type-II alignment relative to a value 1.05 for the ratio (Qv) proposed. Finally, through detailed comparison these values with those published previously, we have shown that scatter in Qv found literature (<1...

Molecular beam epitaxial growth of GaAs nanowires using Au particles as a catalyst was investigated. Prior to the during annealing, alloyed with Ga coming from substrate, and melted. Phase transitions resulting were observed in situ by reflection high-energy electron diffraction (RHEED). The temperature domain which nanowire is possible determined. lower limit this (320 °C) close solidification temperature. Below temperature, buried growth. Above higher (620 °C), segregates on surface no...

The incorporation of nitrogen in the low percentage range is investigated a different III–V compound matrix. materials are grown by molecular-beam epitaxy with radio-frequency plasma source. For equivalent growth conditions, same rate N found for GaAsN and GaInAsN. However, this significantly enhanced GaAsSbN alloy. These observations support discussion on reactive species.