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optical microscopy of crystal growth of graphene using thermal radiationTerasawa, Tomoo; Taira, Takanobu*; Obata, Seiji*; Saiki, Koichiro*; Yasuda, Satoshi; Asaoka, Hidehito
Vacuum and Surface Science, 62(10), p.629 - 634, 2019/10
Graphene, an atomically thin sheet composed of sp
carbon atoms, has been the most attractive material in this decade. The fascinating properties of graphene are exhibited when it is monolayer. Chemical vapor deposition (CVD) is widely used to produce monolayer graphene selectively in large-area. Here we introduce "radiation-mode optical microscopy" which we have developed in order to realize the 
observation of the CVD growth of graphene. We show the method to observe graphene as bright contrast on Cu substrates in thermal radiation images. The growth mechanism, the nucleation site and rate limiting process, revealed by the observation is presented. Finally, we show the CVD growth of graphene on Au substrates, resulting in the tuning of the emissivity of graphene by the pre-treatment procedures. Our method is not only a way to observe the graphene growth but also shed light on the thermal radiation property of graphene.
Terasawa, Tomoo; Taira, Takanobu*; Yasuda, Satoshi; Obata, Seiji*; Saiki, Koichiro*; Asaoka, Hidehito
Japanese Journal of Applied Physics, 58(SI), p.SIIB17_1 - SIIB17_6, 2019/08
Times Cited Count：4 Percentile：21.91(Physics, Applied)Chemical vapor deposition (CVD) on substrates with low C solubility such as Cu and Au is promising to grow monolayer graphene selectively in a large scale. Hydrogen is often added to control the domain size of graphene on Cu, while Au does not require H
since Ar is inert against oxidation. The effect of H should be revealed to improve the quality of graphene on Au. Here we report the effect of H on the CVD growth of graphene on Au substrates using in situ radiation-mode optical microscopy. The in situ observation and ex situ Raman spectroscopy revealed that whether H was supplied or not strongly affected the growth rate, thermal radiation contrast, and compressive strain of graphene on Au. We attributed these features to the surface reconstruction of Au(001) depending on H supply. Our results are essential to achieve the graphene growth with high quality on Au for future applications.
Kakuta, Tsunemi; Yamagishi, Hideshi; Tabata, Hiroaki*; Urakami, Masao*
Dai-7-Kai Doryoku Enerugi Gijutsu Shimpojiumu Koen Rombunshu (00-11), p.254 - 257, 2000/11
no abstracts in English
Terasawa, Tomoo; Taira, Takanobu*; Obata, Seiji*; Yasuda, Satoshi; Saiki, Koichiro*; Asaoka, Hidehito
no journal, ,
Monolayer selective growth of graphene was achieved by chemical vapor deposition on a Cu substrate due to its low carbon solubility. In this study, we attempted the in-situ observation of chemical vapor deposition of graphene on a Au substrate with low carbon solid solubility like Cu by a radiation-mode optical microscopy. In the radiation images, the bright contrast started the growth between the trenches of the Au foil and progressed parallel to the trenches. The result of Raman mapping measurement indiceted that this contrast corresponded to graphene. In the presentation, we will also discuss the growth mechanism of graphene on the Au substrate.
Terasawa, Tomoo; Taira, Takanobu*; Obata, Seiji*; Yasuda, Satoshi; Saiki, Koichiro*; Asaoka, Hidehito
no journal, ,
Since the solubility of carbon in copper is very low, monolayer graphene can be selectively grown by chemical vapor deposition (CVD) on a copper substrate. Thus, CVD growth of graphene is considered the most promising technique for the next-generation electronics. Here we report the CVD growth of graphene on gold substrates which also have the low solubility of carbon. We achieved the in-situ observation of the CVD growth of graphene on a gold foil by radiation-mode optical microscopy (Rad-OM). Figure shows the Rad-OM images of a gold foil at the growth time of 15, 30, and 40 min at 900
C under Ar, H, and CH
gas flow at 240, 8, and 5 sccm, respectively. The bright islands, corresponding to graphene confirmed by Raman spectroscopy, appeared between two trenches of the gold foil and grew parallel to the trenches. We will discuss the growth kinetics of graphene on gold, on the basis of the in-situ Rad-OM observation.
Terasawa, Tomoo; Obata, Seiji*; Yasuda, Satoshi; Saiki, Koichiro*; Asaoka, Hidehito
no journal, ,
no abstracts in English
Terasawa, Tomoo; Yasuda, Satoshi; Hayashi, Naoki*; Norimatsu, Wataru*; Ito, Takahiro*; Machida, Shinichi*; Yano, Masahiro; Saiki, Koichiro*; Asaoka, Hidehito
no journal, ,
We report the band structure of graphene grown on hex-Au(001) using angle resolved photoemission spectroscopy (ARPES). We prepared graphene on hex-Au(001) by chemical vapor deposition and took ARPES image of the sample at AichiSR BL7U. The linear graphene band shows the intensity reduction at the binding energy of approximately 0.9 eV, indicating the modification of band structure of graphene by quasi-one dimensional potential of the hex-Au(001) reconstructed surface.
Terasawa, Tomoo; Yasuda, Satoshi; Hayashi, Naoki*; Norimatsu, Wataru*; Ito, Takahiro*; Machida, Shinichi*; Yano, Masahiro; Saiki, Koichiro*; Asaoka, Hidehito
no journal, ,
Terasawa, Tomoo; Yasuda, Satoshi; Hayashi, Naoki*; Norimatsu, Wataru*; Ito, Takahiro*; Machida, Shinichi*; Asaoka, Hidehito
no journal, ,
Graphene shows absorptivity and emissivity of 2.3% independent from the wavelength, however, the wavelength selectivity of the optical properties is required for device applications. Here we report the observation of the electronic band structure and thermal radiation of graphene grown on hex-Au(001) structure. The thermal radiation of graphene grown on hex-Au(001) was decreased in the optical microscopy which observed the light with the wavelength of 700-900 nm. The same sample showed the modified band structure observed by angle resolved photoemission spectroscopy. We will discuss the relation between the thermal radiation and band structure of graphene on Au substrates.
Terasawa, Tomoo; Yasuda, Satoshi; Hayashi, Naoki*; Norimatsu, Wataru*; Ito, Takahiro*; Machida, Shinichi*; Yano, Masahiro; Saiki, Koichiro*; Asaoka, Hidehito
no journal, ,
Terasawa, Tomoo; Yasuda, Satoshi; Hayashi, Naoki*; Norimatsu, Wataru*; Ito, Takahiro*; Machida, Shinichi*; Asaoka, Hidehito
no journal, ,
no abstracts in English
