Carbon Nanotube Forests on SiC: Structural and Electrical Properties
Because carbon nanotube forest formed by surface decomposition of silicon carbide (CNT forest on SiC) is densely packed and vertically aligned with no entangle parts, it is useful to investigate the electrical properties of dense CNT forest. CNTs atomical
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Carbon Nanotube Forests on SiC: Structural and Electrical Properties Masafumi Inaba, Wataru Norimatsu, Michiko Kusunoki and Hiroshi Kawarada
Abstract Because carbon nanotube forest formed by surface decomposition of silicon carbide (CNT forest on SiC) is densely packed and vertically aligned with no entangle parts, it is useful to investigate the electrical properties of dense CNT forest. CNTs atomically bond to SiC substrates, causing good electrical contact for SiC power devices, where the Schottky barrier height is considerably low as *0.4 eV. CNTs contact with each other in dense CNT forest and contact conductance of CNT/CNT interface can be evaluated as *108 S cm−2. This value corresponds to the tunneling conductance between electron clouds of adjacent graphene sheets. Keywords Carbon nanotube
40.1
Silicon carbide Contact
Introduction
Carbon nanotubes (CNTs) have high one-dimensional current conductivity [1] and high thermal conductivity [2]. A dense forest of vertically aligned CNTs is advantageous for applying these properties because of its high CNT orientation. Although CNTs have the potential to withstand a very high current of up to *109 A cm−2, CNTs are generally used in applications with low conductance, such as CNT electrodes for biosensing [3], supercapacitors [4], and thin-film transistors [5]. Conversely, dense CNT forests are candidates for application in highly conductive devices such as power diodes and transistors. Densely packed CNT forests can be used to evaluate the electrical CNT contact. In this chapter, we evaluate the M. Inaba (&) H. Kawarada Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan e-mail: [email protected] W. Norimatsu M. Kusunoki EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa, Nagoya, Aichi 464-8603, Japan © Springer Nature Singapore Pte Ltd. 2019 Y. Setsuhara et al. (eds.), Novel Structured Metallic and Inorganic Materials, https://doi.org/10.1007/978-981-13-7611-5_40
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Schottky barrier height of the CNT/SiC interface and the contact conductivity of the CNT/CNT interface using a CNT forest formed by SiC surface decomposition. In Sect. 40.2, we introduce the CNT forest on SiC from the viewpoint of formation. In Sect. 40.3, the Schottky barrier height of the CNT/SiC interface is evaluated. In Sect. 40.4, the contact conductivity of the CNT/CNT interface is experimentally evaluated. We summarize this chapter in Sect. 40.5.
40.2
Formation of a CNT Forest on SiC
A CNT forest forms on SiC by surface decomposition [6]. At high temperatures above 1250 °C in vacuum, Si atoms at the surface of SiC are selectively attacked by chamber residual oxygen and sublimate as SiO. This has been confirmed by in situ transmission electron microscopy (TEM) observation [7]. The remaining carbon at the SiC surface first forms a lateral sp2 structure, such as graphene flakes, and then a nanosized double-layer graphene dome structure [8–12]. The dome structures act as CNT caps, and CNTs wit
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