Growth, branching, and kinking of molecular-beam epitaxial 〈110〉 GaAs nanowires

Wu, Zhanghua; Mei, Xiangyang; Kim, D.; Blumin, M.; Ruda, Harry E.; Liu, J. Q.; Kavanagh, K. L.

doi:10.1063/1.1618018

Cited by 123 publications

(96 citation statements)

References 17 publications

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“…We note that multiple periodical twining is also observed at the initial stage of growth, frame number 1, which has already been reported before. [7][8][9] The FFTs of the nanowire and substrate indicate the same crystallographic orientation. The structure of the GaAs appearing at the nanocrater follows also the same orientation.…”

mentioning

confidence: 94%

Nucleation mechanism of gallium-assisted molecular beam epitaxy growth of gallium arsenide nanowires

Morral

Colombo

Abstreiter

et al. 2008

Applied Physics Letters

280

272

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Molecular beam epitaxy Ga-assisted synthesis of GaAs nanowires is demonstrated. The nucleation and growth are seen to be related to the presence of a SiO 2 layer previously deposited on the GaAs wafer. The interaction of the reactive gallium with the SiO 2 pinholes induces the formation of nanocraters, found to be the key for the nucleation of the nanowires. With SiO 2 thicknesses up to 30 nm, nanocraters reach the underlying substrate, resulting into a preferential growth orientation of the nanowires. Possibly related to the formation of nanocraters, we observe an incubation period of 258 s before the nanowires growth is initiated. © 2008 American Institute of Physics. ͓DOI: 10.1063/1.2837191͔Semiconductor nanowires are believed to play a decisive role in the electronic and optoelectronic devices of the 21st century. Up to now, the synthesis of nanowires is mainly based on the vapor-liquid-solid and vapor-solid-solid mechanisms. 1,2 Common in both mechanisms is that a metal nanoparticle gathers and decomposes catalytically the precursor molecules. Supersaturation of the metal droplet follows and leads to the precipitation of a solid phase underneath the droplet in the form of a nanowire. Typically, gold is used as a catalyst. The use of such an extrinsic catalytic metal is in general not desired and some effort has been directed into finding alternatives. 3,4 Recently, catalyst-free growth has been achieved both with metal-organic chemical vapor deposition and molecular beam epitaxy ͑MBE͒. 5,6 This type of growth has always been linked to the existence of a plain or patterned SiO 2 surface, whose role has still to be clarified. To our knowledge, a detailed study on the nucleation stage of the nanowires and an analysis of the role of the SiO 2 are still missing.Nanowires were grown in a Gen-II MBE system. 2 in. GaAs wafers were sputtered with silicon dioxide; the thickness was varied between 20 and 100 nm. In order to ensure a contamination-free surface, the substrates were dipped for 2 s in a 12% HF aqueous solution, nitrogen blow dried, and were immediately after transferred in the load lock of the growth chamber. In order to desorb any remnant adsorbed molecules at the surface, the wafers were heated to 650°C for 30 min prior to growth. The synthesis was carried out at a temperature of 630°C, an arsenic As 4 partial pressure of 8 ϫ 10 −7 mbar, a Ga rate of 0.25 Å / s and under rotation of 4 rpm.We first discuss nanowires which were grown simultaneously on two different halves of GaAs substrates with the ͑001͒ and ͑111͒B orientations. After cleaning of the surface and HF dip, the two halves were still coated with a 6 nm SiO 2 thin film. Cross-sectional scanning electron microscopy ͑SEM͒ measurements of the grown nanowires are shown in Fig. 1. The micrographs clearly reveal that the nanowires mainly grow perpendicular to the substrate in the case of the ͑111͒B GaAs, and with an angle of ϳ35°in the case of the ͑001͒ GaAs. This result clearly proves the existence of a relation between the nanowire orientation and...

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mentioning

confidence: 94%

Nucleation mechanism of gallium-assisted molecular beam epitaxy growth of gallium arsenide nanowires

Morral

Colombo

Abstreiter

et al. 2008

Applied Physics Letters

280

272

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“…The end of these ZB wires invariably shows a kink in growth direction abruptly toward a particular h111i direction most likely (111)B. 22 There are shorter, narrower wires aligned with the h110i wafer edges that are growing completely in a h111i direction. No.…”

Section: Methodsmentioning

confidence: 99%

Faster radial strain relaxation in InAs–GaAs core–shell heterowires

Kavanagh

Saveliev

Blumin

et al. 2012

Journal of Applied Physics

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The structure of wurtzite and zinc blende InAs–GaAs (001) core–shell nanowires grown by molecular beam epitaxy on GaAs (001) substrates has been investigated by transmission electron microscopy. Heterowires with InAs core radii exceeding 11 nm, strain relax through the generation of misfit dislocations, given a GaAs shell thickness greater than 2.5 nm. Strain relaxation is larger in radial directions than axial, particularly for shell thicknesses greater than 5.0 nm, consistent with molecular statics calculations that predict a large shear stress concentration at each interface corner.

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“…[7,8] In VLS growth of semiconductor NWs, several growth directions have been frequently observed, such as <111>, [2] <112>, [3,11,13] and <110>. [7,11,14,15] Recently, we have developed a method of synthesizing II-VI semiconductor NWs based on Au-catalyzed VLS using MBE. [11] We observed that ultrathin ZnSe (or ZnS) NWs grew epitaxially on GaP (111) substrates.…”

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confidence: 99%

The Size‐Dependent Growth Direction of ZnSe Nanowires

et al. 2005

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Single crystalline ZnSe nanowires grown by molecular beam epitaxy technique viaAucatalyzed vapor-liquid-solid reaction showed interesting growth phenomena. Au catalysts initially reacted with the substrate to from binary AuGa2 alloy droplets. The growth direction ZnSe nanowires was mainly determined by the sizes of AuGa2 catalysts. The L-S interface structure at the tip of the NW was the most critical factor influencing the NW growth direction. The size-dependent growth direction of ZnSe nanowires was interpreted based on the estimation of the surface and interface energies of ZnSe nuclei.

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Growth, branching, and kinking of molecular-beam epitaxial 〈110〉 GaAs nanowires

Cited by 123 publications

References 17 publications

Nucleation mechanism of gallium-assisted molecular beam epitaxy growth of gallium arsenide nanowires

Nucleation mechanism of gallium-assisted molecular beam epitaxy growth of gallium arsenide nanowires

Faster radial strain relaxation in InAs–GaAs core–shell heterowires

The Size‐Dependent Growth Direction of ZnSe Nanowires

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