Diameter Limitation in Growth of III-Sb-Containing Nanowire Heterostructures (original) (raw)
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We report the growth of InAs/InAs(1-x)Sb(x) single and double heterostructured nanowires by Au-assisted chemical beam epitaxy. The InAs(1-x)Sb(x) nanowire segments have been characterized in a wide range of antimony compositions. Significant lateral growth is observed at intermediate compositions (x ∼ 0.5), and the nucleation and step-flow mechanism leading to this lateral growth has been identified and described. Additionally, CuPt ordering of the alloy has been observed with high resolution transmission electron microscopy, and it is correlated to the lateral growth process. We also show that it is possible to regrow InAs above the InAsSb alloy segment, at least up to an intermediate antimony composition. Such double heterostructures might find applications both as mid-infrared detectors and as building blocks of electronic devices taking advantage of the outstanding electronic and thermal properties of antimonide compound semiconductors.
Suppression of lateral growth in InAs/InAsSb heterostructured nanowires
Journal of Crystal Growth, 2013
It is well known that a significant lateral growth is observed in the InAsSb sections of InAs/InAsSb heterostructured nanowires (NWs) with intermediate Sb content that prevents the independent control of NW diameter and length. Here we demonstrate that this lateral growth can be suppressed by increasing the growth temperature of the InAsSb segment and by reducing the InAs stem length. Optimized InAsSb sections show good structural and electrical properties. The mechanism driving this reduced lateral growth and its relevance toward the synthesis of highly controlled InAs/InAsSb heterostructured NWs are discussed.
Antimonide Heterostructure Nanowires-Growth, Physics and Devices
Populärvetenskaplig sammanfattning xi List of Papers xiv Abbreviations xvii 1 Background 1.1 This thesis investigates the growth and application of antimonide heterostructure nanowires for low-power electronics. In the rst part of the thesis, GaSb, InSb and InAsSb nanowire growth is presented, and the distinguishing features of the growth are described. It is found that the presence of Sb results in more than 50 at. % group-III concentration in the Au seed particle on top of the nanowires. It is further concluded that the eective V/III ratio inside the seed particle is reduced compared to the outside. This enables the suppression of radial growth with remaining high axial growth rate. Furthermore, the low eective V/III ratio may aect the crystal structure formation, which is pure Zinc-blende in all investigated Sb-based nanowires. The strong segregating properties of Sb results in a strong Sb memory eect, and a diculty to nucleate Sb-based nanowires directly on substrates. The second part of the thesis deals with the growth and application of GaSb/InAs(Sb) nanowires for tunnel device applications. The GaSb/InAs(Sb) nanowire heterojunction has a defect-free crystal structure with an extremely abrupt heterojunction due to an inherent delay before the initiation of InAs(Sb) growth. The Sb carry-over from the GaSb growth step into the InAs growth leads to a high Sb background in the InAs(Sb) segment. The diameter of the heterojunction can be reduced below 30 nm by an in-situ annealing treatment, in which material is selectively etched from the region near the heterojunction. The performance of GaSb/InAs(Sb) tunnel diodes is modeled and measured on fabricated single nanowire devices. The diodes exhibit peak current levels of 67 kA/cm 2 , peak-to-valley current ratio between 2 and 3 at room temperature and a tunnel current at V D =-0.5 V of 1.7 MA/cm 2. The expected performance of GaSb/InAs(Sb) tunnel eld-eect transistors is discussed and preliminary measurement data on top-gated devices with 300 nm gate length is also presented.
Enhanced Sb incorporation in InAsSb nanowires grown by metalorganic vapor phase epitaxy
Applied Physics Letters, 2011
We demonstrate metalorganic vapor phase epitaxy of InAs 1−x Sb x nanowires ͑x = 0.08-0.77͒ for applications in high-speed electronics and long-wavelength optical devices. The composition of the InAsSb nanowires and InAsSb epilayers on the same sample is independently determined using lab-setup high resolution x-ray diffraction, by making use of the size-dependent in-plane broadening of the nanowire Bragg peak. We find that the incorporation of Sb into the nanowires is significantly higher than for planar epitaxy under the same growth conditions. Thermodynamic calculations indicate that this is due to a dramatically decreased effective V/III ratio at the particle/nanowire interface.
Scientific reports, 2017
Self-catalyzed growth of axial GaAs1-xSbx nanowire (NW) arrays with bandgap tuning corresponding to the telecommunication wavelength of 1.3 µm poses a challenge, as the growth mechanism for axial configuration is primarily thermodynamically driven by the vapor-liquid-solid growth process. A systematic study carried out on the effects of group V/III beam equivalent (BEP) ratios and substrate temperature (Tsub) on the chemical composition in NWs and NW density revealed the efficacy of a two-step growth temperature sequence (initiating the growth at relatively higher Tsub = 620 °C and then continuing the growth at lower Tsub) as a promising approach for obtaining high-density NWs at higher Sb compositions. The dependence of the Sb composition in the NWs on the growth parameters investigated has been explained by an analytical relationship between the effective vapor composition and NW composition using relevant kinetic parameters. A two-step growth approach along with a gradual variati...
The self-seeded growth of InAsSb nanowires on silicon by metal-organic vapor phase epitaxy
Journal of Crystal Growth, 2014
We present a study on the growth of InAs 1 À x Sb x alloy nanowires directly on Si (111) substrates via a selfseeded mechanism for the first time. Through varying group V flow rate ratios, InAs 1 À x Sb x nanowires with x ¼from 0 to 0.43 are obtained. It is found that Sb content has a significant effect on the morphology and crystal quality of the formed InAs 1 À x Sb x nanowires. Furthermore, the axial and radial growth rates of the nanowires change in opposite trends with increasing group V flow rate ratio. This indicates that the growth rate of InAs 1 À x Sb x nanowires is ultimately determined by Sb compositions of the nanowires. In addition, the scanning electron microscopy and transmission electron microscopy measurements reveal that the dimensional uniformity and crystal quality of InAsSb nanowires with a small amount of Sb compositions are greatly improved compared to the reference InAs nanowires. The effect mechanism of Sb on the growth of InAs 1 À x Sb x nanowires is clarified, which will be a guide for making high-quality InAs 1 À x Sb x nanowires and relevant heterostructure devices in the future.
Growth mechanism of InAs–InSb heterostructured nanowires grown by chemical beam epitaxy
Journal of Crystal Growth, 2011
We report on the particle diameter dependence of the growth rate of the InSb segment of InAs-InSb heterostructured nanowires grown by chemical beam epitaxy. The analysis of the growth rate reveals that the growth is limited by the Gibbs-Thomson effect and the effect of NW lateral dimensions on the nucleation rate during the layer by layer growth. In the temperature range explored, the surface diffusion of adatoms toward the particle and the growth temperature are not affecting the growth rate.
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Selective area growth (SAG) of semiconductors is a scalable method for fabricating gate-controlled quantum platforms. This letter reports on the adatom diffusion, incorporation, and desorption mechanisms that govern the growth rates of SAG nanowire (NW) arrays. We propose a model for the crystal growth rates that considers two parameter groups: the crystal growth control parameters and the design parameters. Using GaAs and InGaAs SAG NWs as a platform, we show how the design parameters such as NW pitch, width, and orientation have an impact on the growth rates. We demonstrate that by varying the control parameters (i.e., substrate temperature and beam fluxes) source, balance, and sink growth modes may exist in the SAG selectivity window. Using this model, we show that inhomogeneous growth rates can be compensated by tuning the design parameters.
Understanding Sn-seeded InSb nanowire growth
2017
III-Sb semiconductor nanowires have drawn a lot of attention because of their many promising applications, such as thermoelectric generation, low power high efficient electronics and quantum transport. Gold as a catalyst seed particle has been dominating for many years assisting nanowires growth. However, gold is incompatible with silicon-based electronics, which is dominating today. Therefore, finding metals alternative to gold as catalyst seed particles for III–V semiconductor nanowire growth is necessary. Sn was chosen as a promising seed particle for InSb nanowires growth. The most commonly used bottom - up method is the Vapor - Liquid - Solid (VLS) mechanism. This project consisted of both experimental and theoretical components, with the aim to develop the growth of InSb semiconductor nanowires using Sn droplets and Metal Organic Chemical Vapour Deposition (MOCVD). The composition of the Sn seeded InSb nanowires (including the seed particle) were determined by X-ray energy dis...