Tailoring the Vapor–Liquid–Solid Growth toward the Self-Assembly of GaAs Nanowire Junctions

Dai, Xiaoying; Dayeh, Shadi A.; Vaithianathan, V.; Larrue, Alexandre; Wang, Jian; Su, Haibin; Soci, Cesare

doi:10.1021/nl202888e

Cited by 22 publications

(22 citation statements)

References 43 publications

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“…Moreover, the Wulff construction is shown to be reliable to generate initial structures of SiNWs and GeNWs. Finally, our findings can be also useful in investigating of morphology of III-V NWs, such as GaAs, where many of the described features have been experimentally observed [25].…”

Section: Discussionmentioning

confidence: 59%

Revising morphology of 〈111〉-oriented silicon and germanium nanowires

et al. 2015

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By means of ab initio calculations we show that morphology of 111 -oriented silicon and germanium nanowires is defined by {112} and {011} facets. Changes in nanowire morphology are predicted to involve a partial transformation of {011} facets in favor of {112} facets even though the latter ones act as edges between adjacent {011} facets. Our estimates of surface energies clearly indicate a (112) surface to be thermodynamically preferable with respect to a (011) surface for both silicon and germanium. These findings can explain experimental observations of {112} facets in round-like and triangle-like morphologies of 111 -oriented silicon nanowires.Keywords: Nanowire; Morphology; Stability BackgroundNowadays silicon and germanium nanowires (SiNWs and GeNWs) are considered to be promising and, at the same time, accessible building blocks for various applications at nanoscale [1]. In fact, SiNWs and GeNWs having mostly 011 , 111 and 112 orientations can easily be grown by different methods involving the vapor-liquidsolid growth mechanism [1][2][3]. Experimental data also indicate a clear faceting nature of morphology of these nanostructures [3,4] while theoretical calculations of the total energy of SiNWs show morphology, which is characterized by various facets, to be one of the key parameters to define the growth orientation especially at small diameters of the NWs when the surface energy is comparable to or dominates over the volume energy [5].It is also widely accepted that the Wulff construction can predict morphology of a NW on the basis of precise information on surface energies of different surfaces. In the case of silicon the most thermodynamically stable surfaces according to experimental observations are (111), (001), (113) and (011) [6], that is also supported by results of ab initio calculations [7,8]. For germanium one can expect the same issue because of the same nature of chemical bonding in silicon and germanium and of comparable differences in surface energies for various surfaces

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Section: Discussionmentioning

confidence: 59%

Revising morphology of 〈111〉-oriented silicon and germanium nanowires

et al. 2015

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“…For the thicker film (>2 nm), all nanowires grew vertically. It should be noted that the Au catalysts on the tips of neighboring nanowires attract towards each other due to an artificial effect in SEM, possibly caused by the charge from the electron beam when viewed in the SEM [25,26]. Furthermore, despite the differences in diameter and density, the GaAs nanowires catalyzed by the 2-, 3-, and 5-nm films are similar in length (refer to Figure 2f,g,h).…”

Section: Resultsmentioning

confidence: 99%

Quantitative study of GaAs nanowires catalyzed by Au film of different thicknesses

Guo

Sun

et al. 2012

Nanoscale Res Lett

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In this letter, we quantitatively investigated epitaxial GaAs nanowires catalyzed by thin Au films of different thicknesses on GaAs (111)B substrates in a metal-organic chemical vapor deposition reactor. Prior to nanowire growth, the de-wetting of Au thin films to form Au nanoparticles on GaAs (111)B in AsH3 ambient at different temperatures is investigated. It is found that with increasing film thickness, the size of the Au nanoparticles increases while the density of the nanoparticles reduces. Furthermore, higher annealing temperature produces larger Au nanoparticles for a fixed film thickness. As expected, the diameters and densities of the as-grown GaAs nanowires catalyzed by these thin Au films reflect these trends.

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“…Another cause could be the large number of twin defects observed in experimental NWs 9,10,51 and associated {111} sidewall facets. 8,51,52 These facets are characterized by surface reconstructions and associated atomic defects, such as vacancies and adatoms, 42 which likely act as CR hot spots. In Sec.…”

Section: B Charge-recombination Dynamicsmentioning

confidence: 99%

Enhanced charge recombination due to surfaces and twin defects in GaAs nanostructures

Brown

Sheng

Shimamura

et al. 2015

Journal of Applied Physics

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Power conversion efficiency of gallium arsenide (GaAs) nanowire (NW) solar cells is severely limited by enhanced charge recombination (CR) at sidewall surfaces, but its atomistic mechanisms are not well understood. In addition, GaAs NWs usually contain a high density of twin defects that form a twin superlattice, but its effects on CR dynamics are largely unknown. Here, quantum molecular dynamics (QMD) simulations reveal the existence of an intrinsic type-II heterostructure at the (110) GaAs surface. Nonadiabatic quantum molecular dynamics (NAQMD) simulations show that the resulting staggered band alignment causes a photoexcited electron in the bulk to rapidly transfer to the surface. We have found orders-of-magnitude enhancement of the CR rate at the surface compared with the bulk value. Furthermore, QMD and NAQMD simulations show unique surface electronic states at alternating (111)A and (111)B sidewall surfaces of a twinned [111]-oriented GaAs NW, which act as effective CR centers. The calculated large surface recombination velocity quantitatively explains recent experimental observations and provides microscopic understanding of the underlying CR processes. V C 2015 AIP Publishing LLC. [http://dx.

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Tailoring the Vapor–Liquid–Solid Growth toward the Self-Assembly of GaAs Nanowire Junctions

Cited by 22 publications

References 43 publications

Revising morphology of 〈111〉-oriented silicon and germanium nanowires

Revising morphology of 〈111〉-oriented silicon and germanium nanowires

Quantitative study of GaAs nanowires catalyzed by Au film of different thicknesses

Enhanced charge recombination due to surfaces and twin defects in GaAs nanostructures

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