Photomemristors using carbon nanowall/diamond heterojunctions
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Photomemristors using carbon nanowall/diamond heterojunctions Kenji Ueda1,a), Hideharu Itou1, Hidefumi Asano1 1
Department of Materials Physics, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan Address all correspondence to this author. e-mail: [email protected]
a)
Received: 30 May 2018; accepted: 7 December 2018
This work demonstrates the in situ growth of carbon nanowalls (CNWs) on diamond semiconductors by microwave plasma-assisted chemical vapor deposition. The resulting CNW/diamond junctions behave as photomemristors having both photocontrollable multiple resistance states and nonvolatile memory functions. The resistance state (high or low resistance) can be selected by irradiation with blue or violet light in conjunction with the application of a bias voltage, giving a large resistance switching ratio of ;106. The photoinduced resistance switching behaviors are rarely observed and has only been observed in a few materials and/or heterostructures. These junctions also exhibit a photoresponsivity of ;12 A/W, which is much larger than that obtained from photodiodes composed of other materials. These results suggest that CNW/diamond (i.e., carbon sp2/sp3) junctions could have applications in novel photocontrollable devices, which have photosensing, memory, and switching functions.
Introduction Diamond and graphene are common carbon allotropes and have numerous potential applications in electronic devices. Diamond, the sp3 carbon allotrope, can be employed in highpower devices due to its excellent physical properties, including exceptional thermal conductivity (22 W/cm K), a high electric breakdown field (.10 mV/cm), and a high carrier mobility (;4500 cm2/V s) [1, 2]. In contrast, graphene (the sp2 carbon allotrope) can be used in high-frequency devices as a result of its very high carrier mobility (;200,000 cm2/V s) [3, 4] and significant current carrying capacity [5]. These properties originate from the unique band characteristics of this material, which in turn are associated with Dirac cones. Although both diamond and graphene are important electronic materials individually, more recently the interface between diamond and graphene (i.e., the sp3/sp2 interface) has attracted much attention because of the various electronic phenomena associated with it. It has been suggested that heterojunctions using graphene (including vertically aligned graphene) and diamond should exhibit a number of interesting electronic characteristics. As an example, Konabe et al. and Shiga et al. predicted highly efficient photoelectric conversion by multiple exciton generation and spin polarization without magnetic ions at the
ª Materials Research Society 2019
interfaces between diamond and vertically aligned graphene nanoribbons [6, 7]. Ma et al. demonstrated possible band gap opening and the induction of magnetism in graphene layers within graphene/diamond (111) heterostructures [8]. Therefore, graphene and diamond are important not only on their own, but also as building blocks for novel electr
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