Predictive modeling of self-catalyzed III-V nanowire growth

Glas, Frank; Ramdani, Mohammed Réda; Patriarche, G.; Harmand, J. C.

doi:10.1103/physrevb.88.195304

Cited by 188 publications

(462 citation statements)

References 61 publications

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“…In Ref. [12], Glas et al presented a growth model based entirely on the kinetics of the arsenic growth species, combined with the nucleation modeling for two-dimensional GaAs islands emerging from a supersaturated Ga-As droplet. However, the droplet size was considered time-independent, while many experimental works reported that the droplet either swells [4,9,10,14,15] or shrinks [6] during growth.…”

Section: Introductionmentioning

confidence: 99%

“…Ga-catalyzed GaAs NWs [3][4][5][6][7][8][9][10][11][12][13][14] are of particular interest in this respect as they allow one to avoid the unwanted Au contamination, achieve the required crystal-phase purity and use the well-developed techniques of SiO x /Si(111) substrate preparation to organize the Ga droplets before growth. Many fundamental growth features and physical properties of Ga-catalyzed GaAs NWs can be understood through predictive growth modeling.…”

Section: Introductionmentioning

confidence: 99%

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Regimes of radial growth for Ga-catalyzed GaAs nanowires

2016

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We present a non-stationary growth model of Ga-catalyzed GaAs nanowires which is based on the two kinetic equations for the nanowire elongation rate and a time-dependent base radius of the droplet. We show that self-catalyzed nanowire growth is principally different from the Au-catalyzed one because a stationary droplet size cannot be maintained at all times. Close examination of the model enables us to separate different regimes of radial growth in which the droplet shrinks, inflates or converges to a certain stationary size as nanowires grow, depending on the initial droplet radius and the growth conditions. We also discuss some experimental data on the growth modes of Ga-catalyzed GaAs nanowires from the viewpoint of the obtained results.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Regimes of radial growth for Ga-catalyzed GaAs nanowires

2016

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“…36,37 This is explained simply by the fact that the droplet contains more gallium under gallium-rich and less gallium under arsenic-rich conditions and the contact angle changes accordingly. However, in gallium-assisted growth, the droplet is almost pure gallium 30 and hence its shape change with the arsenic flux is less clear and requires special treatment.…”

mentioning

confidence: 99%

“…It has often been assumed 14,21,22,30,42 that, for a given material combination, the contact angle of the droplet is fixed by the surface energetics and hence is maintained by changing the NW top radius under varying V/III flux ratio. This property would have been particularly well justified for galliumcatalyzed GaAs NWs because in this case the droplet is almost pure gallium regardless of the group V flux, and is seated on top of pure GaAs.…”

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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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“…The recent increasing interest in semiconductor NWs stems from the growth mechanisms of such extremely anisotropic structures 103,[134][135][136][137][138][139][140][141] as well as the potential for novel device applications of NWs. [142][143][144][145] One of the notable characteristics shown by III-V semiconductor NWs is the formation of polytypes.…”

Section: Dynamics Of Nw Growthmentioning

confidence: 99%

In situ synchrotron X-ray diffraction study on epitaxial-growth dynamics of III–V semiconductors

Takahasi

2018

Jpn. J. Appl. Phys.

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The application of in situ synchrotron X-ray diffraction (XRD) to the molecular-beam epitaxial (MBE) growth of III-V semiconductors is overviewed along with backgrounds of the diffraction theory and instrumentation. X-rays are sensitive not only to the surface of growing films but also to buried interfacial structures because of their large penetration depth. Moreover, a spatial coherence length up to µm order makes X-rays widely applicable to the characterization of low-dimensional structures, such as quantum dots and wires. In situ XRD studies during growth were performed using an X-ray diffractometer, which was combined with an MBE chamber. X-ray reciprocal space mapping at a speed matching a typical growth rate was achieved using intense X-rays available from a synchrotron light source and an area detector. The importance of measuring the three-dimensional distribution of XRD intensity in a reciprocal space map is demonstrated for the MBE growth of two-, one-, and zero-dimensional structures. A large amount of information about the growth process of two-dimensional InGaAs/GaAs(001) epitaxial films has been provided by three-dimensional X-ray reciprocal mappings, including the anisotropic strain relaxation, the compositional inhomogeneity, and the evolution of surface and interfacial roughness. For one-dimensional GaAs nanowires grown in a Au-catalyzed vapor-liquid-solid mode, the relationship between the diameter of the nanowires and the formation of polytypes has been suggested on the basis of in situ XRD measurements. In situ three-dimensional X-ray reciprocal space mapping is also shown to be useful for determining the lateral and vertical sizes of self-assembled InAs/GaAs(001) quantum dots as well as their internal strain distributions during growth.

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Predictive modeling of self-catalyzed III-V nanowire growth

Cited by 188 publications

References 61 publications

Regimes of radial growth for Ga-catalyzed GaAs nanowires

Regimes of radial growth for Ga-catalyzed GaAs nanowires

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

In situ synchrotron X-ray diffraction study on epitaxial-growth dynamics of III–V semiconductors

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