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Ogawa, Shuichi*; Tsuda, Yasutaka; Sakamoto, Tetsuya*; Okigawa, Yuki*; Masuzawa, Tomoaki*; Yoshigoe, Akitaka; Abukawa, Tadashi*; Yamada, Takatoshi*
Applied Surface Science, 605, p.154748_1 - 154748_6, 2022/12
Times Cited Count：4 Percentile：48.5(Chemistry, Physical)Immersion of graphene in KOH solution improves its mobility on SiO
/Si wafers. This is thought to be due to electron doping by modification with K atoms, but the K atom concentration C
in the graphene has not been clarified yet. In this study, the C was determined by XPS analysis using high-brilliance synchrotron radiation. The time evolution of C was determined by real-time observation, and the C before irradiation of synchrotron radiation was estimated to be 0.94%. The C 1s spectrum shifted to the low binding energy side with the desorption of K atoms. This indicates that the electron doping concentration into graphene is decreasing, and it is experimentally confirmed that K atoms inject electrons into graphene.
species at SiO/Si interfaces in Si dry oxidation; Comparison between p-Si(001) and n-Si(001) surfacesTsuda, Yasutaka; Yoshigoe, Akitaka; Ogawa, Shuichi*; Sakamoto, Tetsuya*; Yamamoto, Yoshiki*; Yamamoto, Yukio*; Takakuwa, Yuji*
Journal of Chemical Physics, 157(23), p.234705_1 - 234705_21, 2022/12
Times Cited Count：0 Percentile：0.01(Chemistry, Physical)
molecule at SiO/Si(001) interface during Si dry oxidationTsuda, Yasutaka; Yoshigoe, Akitaka; Ogawa, Shuichi*; Sakamoto, Tetsuya*; Takakuwa, Yuji*
e-Journal of Surface Science and Nanotechnology (Internet), 21(1), p.30 - 39, 2022/11
O vapor on GaN surfacesSumiya, Masatomo*; Sumita, Masato*; Tsuda, Yasutaka; Sakamoto, Tetsuya; Sang, L.*; Harada, Yoshitomo*; Yoshigoe, Akitaka
Science and Technology of Advanced Materials, 23(1), p.189 - 198, 2022/00
Times Cited Count：4 Percentile：51.62(Materials Science, Multidisciplinary)GaN is an attracting material for power-electronic devices. Understanding the oxidation at GaN surface is important for improving metal-oxide-semiconductor (MOS) devices. In this study, the oxidation at GaN surfaces depending on the GaN crystal planes (+c, -c, and m-plane) was investigated by real time XPS and DFT-MD simulation. We found that HO vapor has the highest reactivity due to the spin interaction between HO and GaN surfaces. The bond length between the Ga and N on the -c GaN surface was increased by OH attacking the back side of three-fold Ga atom. The chemisorption on the m-plane was dominant. The intense reactions of oxidation and Al
Ga
N formation for p-GaN were observed at the interface of the AlO
layer deposited by ALD using HO vapor. This study suggests that an oxidant gas other than HO and O should be used to avoid unintentional oxidation during AlGaN atomi layer deposition.
(001) surface using supersonic seeded oxygen molecular beamKatsube, Daiki*; Ono, Shinya*; Takayanagi, Shuhei*; Ojima, Shoki*; Maeda, Motoyasu*; Origuchi, Naoki*; Ogawa, Arata*; Ikeda, Natsuki*; Aoyagi, Yoshihide*; Kabutoya, Yuito*; et al.
Langmuir, 37(42), p.12313 - 12317, 2021/10
Times Cited Count：1 Percentile：6.77(Chemistry, Multidisciplinary)We investigated the oxidation of oxygen vacancies at the surface of anatase TiO(001) using supersonic seeded molecular beam (SSMB) of oxygen. The oxygen vacancies at the top-surface and sub-surface could be eliminated by the supply of oxygen using an SSMB. These results indicate that the interstitial vacancies can be mostly assigned to oxygen vacancies, which can be effectively eliminated by using an oxygen SSMB. Oxygen vacancies are present on the surface of anatase TiO(001) when it is untreated before transfer to a vacuum chamber. These vacancies, which are stable in the as-grown condition, could also be effectively eliminated using the oxygen SSMB.
Tsuda, Yasutaka; Sakamoto, Tetsuya; Yoshigoe, Akitaka
no journal, ,
no abstracts in English
and SR ON-OFF on band bending at SiO/Si(001) interfacesTsuda, Yasutaka; Ogawa, Shuichi*; Yoshigoe, Akitaka; Sakamoto, Tetsuya; Takakuwa, Yuji*
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no abstracts in English
1 surface oxidation at room temperatureYoshigoe, Akitaka; Tsuda, Yasutaka; Tominaga, Aki; Sakamoto, Tetsuya; Ogawa, Shuichi*; Takakuwa, Yuji*
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In Society 5.0, nanometer-scaled devices with high performance and low-power are required. Since silicon (Si) based metal-oxide-semiconductor (MOS) transistors play an important role in the application of information and communication technology, precise control and understanding of Si surface oxidation is still important. However, the debate on the Si surface oxidation by molecular oxygen still remains. In our previous study, we found that the O1s photoelectron spectra of room temperature oxidation of Si(001)21 surface show satellite peaks indicating molecularly adsorbed oxygen. In this study, the role of molecularly adsorbed oxygen in the oxidation reaction in relation to the translational energy of incident oxygen molecules was investigated by synchrotron radiation real-time photoemission spectroscopy. All experiments were conducted using the surface experimental station of JAEA's BL23SU at SPring-8. Even on a p-type Si(001) surface under molecular beam irradiation with the translational energy of 0.06 eV, a satellite peak was clearly observed at a binding energy of about 4.45 eV lower than the main peak (oxygen atom in Si-O-Si). The role of molecularly adsorption in the oxidation reaction will be discussed from the results of signal changes with the progress of oxidation times.
Tsuda, Yasutaka; Sakamoto, Tetsuya; Yoshigoe, Akitaka
no journal, ,
Germanium (Ge) is an important alternative channel material for metal oxide semiconductor field effect transistors (MOSFETs) due to its high carrier mobility. An atomically controlled insulator/Ge interface is essential to improve MOSFET performance. Therefore, it is necessary to understand and control the oxidation process of the Ge surface at the atomic level. On the other hand, the understanding of the oxidation process on the Ge surface is not sufficiently advanced compared to that of silicon (Si), a widely used semiconductor. In this study, we investigated the oxidation process of Ge(110), which is an important low index surface, aiming at a unified understanding of Ge surface oxidation. The oxidation process of Ge(110) was measured by using synchrotron radiation X ray photoemission spectroscopy and compared with that of Ge(100) and Ge(111).
1 surface oxidation at room temperatureYoshigoe, Akitaka; Tsuda, Yasutaka; Tominaga, Aki; Sakamoto, Tetsuya; Ogawa, Shuichi*; Takakuwa, Yuji*
no journal, ,
The basic understanding of the oxidation at Si surfaces by oxygen gas has been important to develop advanced metal-oxide-semiconductor devices. In our previous study, we succeeded to detect a satellite peak located at lower binding energy sides of the main peak (Si-O-Si) in the Si(001)21 surface oxidation. This peak has been considered to be due to the molecularly adsorbed oxygen. In this study, we studied the incident O energy dependence of this adsorbate by using real-time photoemission spectroscopy. All experiments were conducted at the surface experimental station (SUREAC2000) at BL23SU in SPring-8. It was found that the satellite peak was clearly observed. This result also implies the existence of a precursor state of adsorbed oxygen dissociation even for 0.06 eV.
/n- and p-Si(001) interfacesTsuda, Yasutaka; Ogawa, Shuichi*; Yoshigoe, Akitaka; Sakamoto, Tetsuya; Takakuwa, Yuji*
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/Si(001) interfacial oxidationTsuda, Yasutaka; Ogawa, Shuichi*; Yoshigoe, Akitaka; Tominaga, Aki; Sakamoto, Tetsuya; Yamamoto, Yoshiki*; Yamamoto, Yukio*; Takakuwa, Yuji*
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no abstracts in English
on oxidation at SiO/Si(001) interfaceTsuda, Yasutaka; Yoshigoe, Akitaka; Ogawa, Shuichi*; Sakamoto, Tetsuya*; Takakuwa, Yuji
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/Si(001) interface by molecularly-adsorbed OTsuda, Yasutaka; Yoshigoe, Akitaka; Ogawa, Shuichi*; Sakamoto, Tetsuya*; Takakuwa, Yuji
no journal, ,
no abstracts in English
Sumiya, Masatomo*; Tsuda, Yasutaka; Sakamoto, Tetsuya*; Sumita, Masato*; Sang, L.*; Harada, Yoshitomo*; Yoshigoe, Akitaka
no journal, ,
no abstracts in English
species at SiO/Si interfaces in Si dry oxidationTsuda, Yasutaka; Yoshigoe, Akitaka; Ogawa, Shuichi*; Sakamoto, Tetsuya*; Yamamoto, Yoshiki*; Yamamoto, Yukio*; Takakuwa, Yuji*
no journal, ,
no abstracts in English
