The Synergic Effect of Atomic Hydrogen Adsorption and Catalyst Spreading on Ge Nanowire Growth Orientation and Kinking

Kolı́bal, Miroslav; Pejchal, Tomáš; Vystavel, T.; Šikola, Tomáš

doi:10.1021/acs.nanolett.6b01352

Cited by 21 publications

(25 citation statements)

References 48 publications

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“…Homoepitaxial growth of Ge NWs (Fig. 1a) has been well documented before [25,27] and our growth results are in agreement with previous reports. Ge NWs grow in the <110> direction (perpendicular to the substrate surface plane), with a well-defined growth interface (two-inclined {111} facets) and shape (rhombohedral cross-section, {111}-oriented sidewall facets).…”

Section: Accepted Manuscriptsupporting

confidence: 93%

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Catalyst–substrate interaction and growth delay in vapor–liquid–solid nanowire growth

et al. 2018

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Understanding of the initial stage of nanowire growth on a bulk substrate is crucial for the rational design of nanowire building blocks in future electronic and optoelectronic devices. Here, we provide in situ scanning electron microscopy and Auger microscopy analysis of the initial stage of Au-catalyzed Ge nanowire growth on different substrates. Real-time microscopy imaging and elementally resolved spectroscopy clearly show that the catalyst dissolves the underlying substrate if held above a certain temperature. If the substrate dissolution is blocked (or in the case of heteroepitaxy) the catalyst needs to be filled with nanowire material from the external supply, which significantly increases the initial growth delay. The experiments presented here reveal the important role of the substrate in metal-catalyzed nanowire growth and pave the way for different growth delay mitigation strategies.

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Section: Accepted Manuscriptsupporting

confidence: 93%

“…We have conducted nanowire growth in two growth chambers, which were already described in detail previously [25]. The first one is an ultra-high-vacuum chamber connected to an Auger Electron Microscope (AEM, Omicron).…”

Section: Methodsmentioning

confidence: 99%

Catalyst–substrate interaction and growth delay in vapor–liquid–solid nanowire growth

et al. 2018

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“…In Fig. 5(c), we notice that some of NWs have a droplet on the their top or sidewall, while some NWs have lost this possibly because of catalyst spreading 24 and Ostwald ripening process 28 during the long growth time of VLS at relatively high temperature. Figure 5(b) also shows the low density of Ge NWs grown at 470 C caused by two possible aspects: (i) the catalyst separation is much larger than the surface diffusion length so that some of the adatoms cannot reach the catalyst to form NWs and nucleate as islands, and (ii) long-time and high-temperature growth leads to catalyst migration, which can stop NW growth.…”

Section: (B)mentioning

confidence: 97%

“…All these morphological differences in both the growth orientation and the NW diameter can be explained by the fundamental growth mechanism in the VSS and the VLS processes. The Ge (110) substrate is selected because Ge NWs grow along h110i by VLS without atomic hydrogen environment, 24 and most of the Ge NWs are vertical to the Ge (110) substrate. 10 EXPERIMENT Ge NWs were grown via a DCA P450 solid source MBE system.…”

Section: B)mentioning

confidence: 99%

Vapor-solid-solid grown Ge nanowires at integrated circuit compatible temperature by molecular beam epitaxy

Zhu

Song

Zhang

et al. 2017

Journal of Applied Physics

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We demonstrate Au-assisted vapor-solid-solid (VSS) growth of Ge nanowires (NWs) by molecular beam epitaxy at the substrate temperature of $180 C, which is compatible with the temperature window for Si-based integrated circuit. Low temperature grown Ge NWs hold a smaller size, similar uniformity, and better fit with Au tips in diameter, in contrast to Ge NWs grown at around or above the eutectic temperature of Au-Ge alloy in the vapor-liquid-solid (VLS) growth. Six h110i growth orientations were observed on Ge (110) by the VSS growth at $180 C, differing from only one vertical growth direction of Ge NWs by the VLS growth at a high temperature. The evolution of NWs dimension and morphology from the VLS growth to the VSS growth is qualitatively explained by analyzing the mechanism of the two growth modes. Published by AIP Publishing.

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“…In this contribution we introduce an integration of two new modules fulfilling these requirements by allowing in-situ heating in FIB/SEM systems under high vacuum conditions. Moreover, heating in high vacuum combined with injection of selected gases was also proven capable of providing sample surface oxidation [1] or reduction ( Figure 1), [2].…”

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confidence: 99%

New approaches to in-situ heating in FIB/SEM systems

Novák

Wandrol

et al. 2017

Microsc Microanal

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Over last decades significant effort has been made on in-situ heating experiments inside SEM and FIB/SEM chambers. Traditional way is to use low vacuum environment in the entire chamber. Although this valuable approach brings various undeniable advantages, new state of the art experiments coincide with new requirements, such as rapid changes in temperature, high-vacuum operation to maximize experiment cleanliness, ultra-high resolution SEM imaging and on top of it adaptable geometry in order to investigate sample's crystallography and composition changes using EBSD and EDS detectors. In this contribution we introduce an integration of two new modules fulfilling these requirements by allowing in-situ heating in FIB/SEM systems under high vacuum conditions. Moreover, heating in high vacuum combined with injection of selected gases was also proven capable of providing sample surfaceThe module choice essentially depends on the sample size and the type of analysis required. For millimeter-sized samples, a bulk heating stage can be selected, which allows a heating rate of unit degrees per second for heating up to 1000°C. The heating stage is made of materials with negligible outgassing that assures experiment cleanness and can also provide high vacuum environment arround the heated sample with SEM chamber pressure in the order of 10-5 Pa. In-situ observation of microstructure evolution can be achieved by standard SEM detectors collecting SE and BSE signal passing through a user replaceable heat shield, which protects sensitive parts in SEM chamber from overheating. In addition, geometry of a dedicated heat shield permits EBSD mapping as well as EDS analysis of a heated sample placed on this heating stage. However, quality of the EDS and EBSD data is influenced by infrared radiation interference at temperatures above 600°C. This background can be reduced to minimum by employing a microheatingplate device.A novel microheatingplate device based on microelectromechanical systems (MEMS) technology provides a maximum temperature of 1200°C and a very high heating/cooling rate in the order of 10 5 degrees per second [3]. This MEMS chip is able to support nano-scale to sub-millimeter-sized samples (samples with dimensions in tens of µm are typically used). In-situ imaging of samples placed on the MEMS chip during heating can be obtained using all types of detectors [4] including STEM, EBSD and EDS. The localised heating and small thermal mass capacity bear indespensible merits such as high uniformity of the heating area, high stability even during operations above 1000°C, site specification and minor sample displacement and drift stablilization. Chunk samples (typically metallic samples for Materials Science research) can be first fabricated using FIB milling in the bulk, then in-situ lifted out, welded on the MEMS chip and optionally the sample surface can be cleaned with low kV ions. We present in Figure 2 EBSD results of microstructure evolution of a slightly deformed Ti6Al4V chunk sample obtained during in-situ heating at ...

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The Synergic Effect of Atomic Hydrogen Adsorption and Catalyst Spreading on Ge Nanowire Growth Orientation and Kinking

Cited by 21 publications

References 48 publications

Catalyst–substrate interaction and growth delay in vapor–liquid–solid nanowire growth

Catalyst–substrate interaction and growth delay in vapor–liquid–solid nanowire growth

Vapor-solid-solid grown Ge nanowires at integrated circuit compatible temperature by molecular beam epitaxy

New approaches to in-situ heating in FIB/SEM systems

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