Surface energy and crystal structure of nanowhiskers of III–V semiconductor compounds

Sibirev, N. V.; Timofeeva, Maria; Bolshakov, A D; Назаренко, М. В.; Dubrovskiı̆, V. G.

doi:10.1134/s1063783410070309

Cited by 84 publications

(93 citation statements)

References 21 publications

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“…However, implementing reported values for surface energies in the literature [33], which is a measure of g , j A do not show any significant differences between the stability of {¯} 0110 facets of the stem and the {¯} 1120 facets of the kink. Alternatively, differences in absorption efficiency or in thermal dissipation could be a consequence of the differences in geometry of the two types of NWs and thereby explain the observed selectivity.…”

Section: B Amentioning

confidence: 84%

Morphology and composition of oxidized InAs nanowires studied by combined Raman spectroscopy and transmission electron microscopy

et al. 2016

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Any device exposed to ambient conditions will be prone to oxidation. This may be of particular importance for semiconductor nanowires because of the high surface-to-volume ratio and only little is known about the consequences of oxidation for these systems. Here, we study the properties of indium arsenide nanowires which were locally oxidized using a focused laser beam. Polarization dependent micro-Raman measurements confirmed the presence of crystalline arsenic, and transmission electron microscopy diffraction showed the presence of indium oxide. The surface dependence of the oxidation was investigated in branched nanowires grown along the [ ] 0001 and [¯] 0110 wurtzite crystal directions exhibiting different surface facets. The oxidation did not occur at the [¯] 0110 direction. The origin of this selectivity is discussed in terms transition state kinetics of the free surfaces of the different crystal families of the facets and numerical simulations of the laser induced heating.

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Section: B Amentioning

confidence: 84%

Morphology and composition of oxidized InAs nanowires studied by combined Raman spectroscopy and transmission electron microscopy

et al. 2016

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“…For the WZ sidewall surface energy γ WV we use values taken from Ref. 27: γ WV (WZ1100) = 1.30 J/m 2 and γ WV (WZ1120) = 1.54 J/m 2 . The solid-liquid surface energy, γ SL = 0.59 J/m 2 , is identical for the ZB and WZ nuclei due to the close atomic environments on the surface around the two types of nuclei.…”

Section: Comparison With the Nucleation Theorymentioning

confidence: 99%

Transition from Au to pseudo-Ga catalyzed growth mode observed in GaAs nanowires grown by molecular beam epitaxy

et al. 2012

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We investigate the correlation between the Ga concentration of the catalyst droplet and the adopted crystal structure of individual GaAs nanowires grown by molecular-beam epitaxy using Au as a catalyst material. Through a postgrowth analysis the Ga content of the catalyst droplet during growth is estimated and related to the observed crystal structure of the nanowires. Depending on the Ga concentration, we observe a transition from typical Au catalyzed to pseudo-Ga assisted nanowire growth: Nanowires with low Ga concentration of the catalyst droplet during growth form predominantly wurtzite crystal structures. For Ga concentrations higher than 75 at. %, which we refer to as the pseudo-Ga assisted growth mode, the probability to form zinc-blende segments is strongly enhanced owing to the reduced droplet surface energy of the catalyst.

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“…Finally, the droplet is stable against random horizontal shift smaller than the top facet only when the contact angle exceeds the equilibrium Young's angle β * given by cos β * = (γ SV − γ SL )/γ LV , with γ SV as the solid−vapor surface energy of the top facet (ref 39). The Young's angle equals approximately 70°at γ SV = 0.64 J/m 2 (the surface energy of (111) top plane should be about 20% lower than that of (110) plane according to ref 48). For high enough arsenic flux, the contact angle may decrease faster than the inward tapered facets are introduced and then shrink smaller than the top facet to resume the equilibrium droplet shape, as illustrated by scenario "(iii) Shrinkage" in Figure 4b.…”

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confidence: 99%

Bistability of Contact Angle and Its Role in Achieving Quantum-Thin Self-Assisted GaAs nanowires

et al. 2017

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Achieving quantum confinement by bottom-up growth of nanowires has so far been limited to the ability of obtaining stable metal droplets of radii around 10 nm or less. This is within reach for gold-assisted growth. Because of the necessity to maintain the group III droplets during growth, direct synthesis of quantum sized structures becomes much more challenging for self-assisted III−V nanowires. In this work, we elucidate and solve the challenges that involve the synthesis of galliumassisted quantum-sized GaAs nanowires. We demonstrate the existence of two stable contact angles for the gallium droplet on top of GaAs nanowires. Contact angle around 130°fosters a continuous increase in the nanowire radius, while 90°allows for the stable growth of ultrathin tops. The experimental results are fully consistent with our model that explains the observed morphological evolution under the two different scenarios. We provide a generalized theory of self-assisted III−V nanowires that describes simultaneously the droplet shape relaxation and the NW radius evolution. Bistability of the contact angle described here should be the general phenomenon that pertains for any vapor−liquid−solid nanowires and significantly refines our picture of how nanowires grow. Overall, our results suggest a new path for obtaining ultrathin one-dimensional III−V nanostructures for studying lateral confinement of carriers. KEYWORDS: III−V semiconductors on silicon, nanowires, nanoneedles, regular arrays, self-assisted growth, droplet size engineering, crystal structure, growth modeling F undamental physical properties and applications of semiconductor nanowires (NWs) may benefit from quantum confinement due to size-dependent modulation of the density of states as well as modification of the photon energy for the allowed optical transitions.1 In GaAs, quantum confinement occurs for a size below 25 nm.2,3 In addition to quantum confinement, the optical properties can be engineered by modifying the NW shape. For example, progressively tapered nanowires have exhibited adiabatic outcoupling in the emission of quantum dots, thereby enhancing their brightness. 4 A similar design may improve the light extraction or absorption in different optoelectronic devices including light emitting diodes, solar cells, and optical biosensors.5−11 Quantum confinement in the core of radial NW heterostructures allows for the fabrication of high quality NW-based quantum dots, which are a perfect platform for delicate quantum transport experiments. 12,13 It is admittedly challenging to obtain very thin (quantumconfined) III−V NWs directly by the vapor−liquid−solid (VLS) growth technique. There are several reasons for that (see ref 14 for a review), including the Gibbs−Thomson effect of elevation of chemical potential due to the curvature of the droplet surface and difficulties in obtaining very small droplets on the substrate surface. Thin tips of VLS GaAs NWs with a stable radius down to 5 nm have previously been grown by hydride vapor phase epitaxy 15,16 (a te...

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Surface energy and crystal structure of nanowhiskers of III–V semiconductor compounds

Cited by 84 publications

References 21 publications

Morphology and composition of oxidized InAs nanowires studied by combined Raman spectroscopy and transmission electron microscopy

Morphology and composition of oxidized InAs nanowires studied by combined Raman spectroscopy and transmission electron microscopy

Transition from Au to pseudo-Ga catalyzed growth mode observed in GaAs nanowires grown by molecular beam epitaxy

Bistability of Contact Angle and Its Role in Achieving Quantum-Thin Self-Assisted GaAs nanowires

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