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Kusano, Kanya*; Ichimoto, Kiyoshi*; Ishii, Mamoru*; Miyoshi, Yoshizumi*; Yoden, Shigeo*; Akiyoshi, Hideharu*; Asai, Ayumi*; Ebihara, Yusuke*; Fujiwara, Hitoshi*; Goto, Tadanori*; et al.
Earth, Planets and Space (Internet), 73(1), p.159_1 - 159_29, 2021/12
Times Cited Count：6 Percentile：51.19(Geosciences, Multidisciplinary)The PSTEP is a nationwide research collaboration in Japan and was conducted from April 2015 to March 2020, supported by a Grant-in-Aid for Scientific Research on Innovative Areas from the Ministry of Education, Culture, Sports, Science and Technology of Japan. It has made a significant progress in space weather research and operational forecasts, publishing over 500 refereed journal papers and organizing four international symposiums, various workshops and seminars, and summer school for graduate students at Rikubetsu in 2017. This paper is a summary report of the PSTEP and describes the major research achievements it produced.
Sato, Masayuki*; Muraoka, Koji*; Hozumi, Koki*; Sanada, Yukihisa; Yamada, Tsutomu*; Torii, Tatsuo
Nihon Koku Uchu Gakkai Rombunshu (Internet), 65(2), p.54 - 63, 2017/02
This paper is concerned with the design problem of preview altitude controller for Unmanned Airplane for Radiation Monitoring System (UARMS) to improve its control performance. UARMS has been developed for radiation monitoring around Fukushima Daiichi Nuclear Power Plant which spread radiation contaminant due to the huge tsunamis caused by the Great East Japan Earthquake. The monitoring area contains flat as well as mountain areas. The basic flight controller has been confirmed to have satisfactory performance with respect to altitude holding; however, the control performance for variable altitude commands is not sufficient for practical use in mountain areas. We therefore design preview altitude controller with only proportional gains by considering the practicality and the strong requirement of safety for UARMS. Control performance of the designed preview controller was evaluated by flight tests conducted around Fukushima Sky Park.
Yamaguchi, Hisato*; Ogawa, Shuichi*; Watanabe, Daiki*; Hozumi, Hideaki*; Gao, Y.*; Eda, Goki*; Mattevi, C.*; Fujita, Takeshi*; Yoshigoe, Akitaka; Ishizuka, Shinji*; et al.
Physica Status Solidi (A), 213(9), p.2380 - 2386, 2016/09
Times Cited Count：13 Percentile：52.49(Materials Science, Multidisciplinary)We report valence-band electronic structure evolution of graphene oxide (GO) upon its thermal reduction. The degree of oxygen functionalization was controlled by annealing temperature, and an electronic structure evolution was monitored using real-time ultraviolet photoelectron spectroscopy. We observed a drastic increase in the density of states around the Fermi level upon thermal annealing at 
600
C. The result indicates that while there is an apparent bandgap for GO prior to a thermal reduction, the gap closes after an annealing around that temperature. This trend of bandgap closure was correlated with the electrical, chemical, and structural properties to determine a set of GO material properties that is optimal for optoelectronics. The results revealed that annealing at a temperature of 500C leads to the desired properties, demonstrated by a uniform and an order of magnitude enhanced photocurrent map of an individual GO sheet compared to an as-synthesized counterpart.
Ge
alloy layer studied by real-time photoelectron spectroscopyOgawa, Shuichi*; Hozumi, Hideaki*; Yoshigoe, Akitaka; Ishizuka, Shinji*; Kaga, Toshiteru*; Teraoka, Yuden; Takakuwa, Yuji*
Oyo Butsuri Gakkai Hakumaku, Hyomen Butsuri Bunkakai, Shirikon Tekunoroji Bunkakai Kyosai Tokubetsu Kenkyukai Kenkyu Hokoku, p.67 - 70, 2011/01
The oxidation-enhanced Ge atoms condensation kinetics on an SiGe alloy layer has been investigated by the real-time photoemission spectroscopy using the synchrotron radiation. The SiGe alloy layer was formed with a thermal evaporation method on a p-type Si(001) surface, and this alloy layer was oxidized at Langmuir-type adsorption. During oxidation at 773 KC, it is found that the Ge atoms are not oxidized, only SiO
film is formed on the SiGe alloy layer. Furthermore, the desorption of GeO molecules does not occur during the oxidation of alloy layer. On the other hand, not only Si atoms but also Ge atoms are oxidized at room temperature. This difference can be explained using the unified oxidation model mediated by the point defect generation, namely it is suggested that a lot of vacancies are generated during oxidation of the SiGe alloy layer at 773K and Ge atoms diffuse through these vacancies.
Katata, Genki; Nagai, Haruyasu; Kajino, Mizuo*; Ueda, Hiromasa*; Hozumi, Yu*
Agricultural and Forest Meteorology, 150(3), p.340 - 353, 2010/03
Times Cited Count：31 Percentile：76.95(Agronomy)The aim of the present study is to evaluate fog deposition on vegetation and its contribution to water and energy balance in arid regions using a detailed land surface model including fog deposition on vegetation under meteorological conditions simulated by a meteorological model. The results of estimated fog deposition indicated that fog deposition provided a more effective water source for plant growth as compared to heavy rainfall in arid areas. Evaporation from leaf surface water eases the plant's water stress via reducing transpiration. Latent heat of evaporation from the leaf surface water and soil causes temperature reduction of soil and leaves during the daytime. Moreover, decreased transpiration rates as a result of increased evaporation from the leaf surface water due to fog deposition, yields an effective water source to be used for photosynthesis for those plants suffering from severe water stress in arid environments.
C alloy layer/Si(001) surface under oxide growth and etching conditionsHozumi, Hideaki*; Ogawa, Shuichi*; Yoshigoe, Akitaka; Ishizuka, Shinji*; Harries, J.; Teraoka, Yuden; Takakuwa, Yuji*
Oyo Butsuri Gakkai Hakumaku, Hyomen Butsuri Bunkakai, Shirikon Tekunoroji Bunkakai Kyosai Tokubetsu Kenkyukai Kenkyu Hokoku, p.181 - 184, 2010/01
The oxidation kinetics on the SiC alloy layer has been investigated using the real-time XPS measurement. Experiments were performed at the BL23SU of SPring-8. The SiC alloy layer was formed with exposing a p-type Si(001) surface to ethylene, and the SiC alloy layer was oxidized at Langmuir-type adsorption (773 K) and 2D oxide island growth (933 K), respectively. In case of Langmuir-type adsorption, it is found that no carbon atoms are oxidized and carbon concentration at the SiO/Si interface increases. These results indicate the carbon atom condensation occurs, leading to the SiO/SiC/Si layers formation. On the other hand, the carbon concentration decrease by 20% in spite of the etching of 38 Si layers in the 2D oxide island growth. Based on these results, it is found that the diffusion of carbon atoms is occurred due to not only oxide growth but also Si etching.
Hozumi, Hideaki*; Ogawa, Shuichi*; Yoshigoe, Akitaka; Ishizuka, Shinji*; Harries, J.; Teraoka, Yuden; Takakuwa, Yuji*
JSPS 141 Committee Activity Report, p.317 - 322, 2009/12
It is reported that SiC alloy layer was formed on an Si(001) surface with CH
exposure at 933 K before nucleation. However information of the chemical bonding state and concentration of adsorbed carbon has not been clear. Therefore the carbonization reaction kinetics on an Si(001) surface reacted with CH exposure was observed by real-time XPS to investigate the 3C-SiC nucleation kinetics. The experiments were performed at the BL23SU of SPring-8. It is suggested that the C1s spectra is composed of at least three chemically-shifted components, which are assigned to carbon-poor SiC alloy, carbon-rich SiC alloy and 3C-SiC. The 3C-SiC nuclei began to generate at 8000s. Using C1s and Si2p
peaks, carbon concentration of the SiC alloy layer was estimated to be about 0.17 of x. Therefore it is suggested that critical carbon concentration is 17%.
Ogawa, Shuichi*; Hozumi, Hideaki*; Yoshigoe, Akitaka; Ishizuka, Shinji*; Teraoka, Yuden; Takakuwa, Yuji*
no journal, ,
In this study, real-time XPS observation of Si(001) surface oxidation is employed to investigate the surface oxidation reaction manner dependence of SiO/Si interface and growth rate of the second oxide layer. Oxidation experiments were performed at the surface reaction analysis apparatus placed at BL23SU, SPring-8. A p-type Si(001) surface was oxidized by dry oxygen. In the Langmuir-type adsorption, the amount of strained Si atoms at the end of surface oxidation is 0.46 ML, and then significant interface oxidation can be observed. On the other hand, in the 2D oxide island growth, the amount of strained Si atoms is 0.15 ML and progress of interface oxidation hardly observed. These results indicate that when interface strain is large, the interface oxidation rate also large, and then that strongly depends on Si surface oxidation manner.
Takakuwa, Yuji*; Ogawa, Shuichi*; Hozumi, Hideaki*; Kawamura, Tomofumi*; Yoshigoe, Akitaka; Ishizuka, Shinji*; Teraoka, Yuden
no journal, ,
In order to investigate the surface reaction kinetics on SiC alloy layer, the carbonization reaction on Si(001) surface by ethylene using the real-time XPS observation by synchrotron radiation. Experiments were performed at the surface reaction analysis apparatus placed at BL23SU, SPring-8. A p-type Si(001) surface heated as 913 K was carbonized using CH diluted by He. It is found from Si 2p photoelectron spectra that Si-C bounding component increases in proportion as dosage of CH, and same tendency is observed from dosage dependence of C 1s photoelectron intensity. These results indicate that the dissociative adsorption of CH on Si(001) surface is zero-order reaction, and the activation energy of diffusion of adsorbed C atoms into Si subsurface is very small.
Hozumi, Hideaki*; Ogawa, Shuichi*; Yoshigoe, Akitaka; Ishizuka, Shinji*; Teraoka, Yuden; Takakuwa, Yuji*
no journal, ,
In this study, real-time XPS was applied to investigate the effect of lattice strain due to the dimerization on an Si(001) surface. The SiC alloy layer was formed on a p-type Si(001) surface by CH exposure. Carbonization and oxidation reactions were observed by XPS to investigate the oxidation rate and behavior of C atom. Experiments were performed using the surface reaction analysis apparatus placed at the BL23SU of SPring-8. The photoelectron spectroscopy measurement of C1s, O1s and Si2p was performed during carbonization and oxidation on an Si(001) surface. Oxidation rate on carbonized Si(001) surface was faster than that on clean Si(001) surface. Since C1s intensity was almost constant during oxidation, it is suggested that C atoms did not exist in SiO and diffuse into the Si substrate.
C alloy layer on Si(001) substrateHozumi, Hideaki*; Ogawa, Shuichi*; Yoshigoe, Akitaka; Ishizuka, Shinji*; Teraoka, Yuden; Takakuwa, Yuji*
no journal, ,
We investigated that the effect of lattice strain due to displacement for hetero atom on an Si(001) surface by real-time XPS. The SiC alloy layer was formed on a p-type Si(001) surface by carbonization with CH exposure. The oxidation kinesics on the carbonized surface was compared with that on a clean Si surface. Experiments were performed using the surface reaction analysis apparatus placed at the BL23SU of SPring-8. The X-ray photoelectron spectroscopy measurement of C1s, O1s and Si2p was performed during carbonization and oxidation. Oxidation rate on the carbonized surface was faster than that on the clean surface. C1s intensity normalized by Si bulk intensity was almost constant during surface oxidation and then decreased slowly during interface oxidation. It suggests that C atom did not exist in SiO layer and diffuse into the Si substrate.
/Si(001) interfaceHozumi, Hideaki*; Ogawa, Shuichi*; Yoshigoe, Akitaka; Ishizuka, Shinji*; Teraoka, Yuden; Takakuwa, Yuji*
no journal, ,
The oxidation kinetics of SiC layer prepared with CH exposure was observed by real-time XPS to investigate effects of substrate stress due to displacement of hetero atom on a p-type Si(001) surface. Experiments were performed using the surface reaction analysis apparatus placed at the BL23SU of SPring-8. Oxidation rate on the SiC layer was larger than that of a clean surface. It was found that carbon atoms diffused into substrate without CO or CO desorption during oxidation. Furthermore "an unified Si oxidation reaction model mediated by point defect generation" could explain these results with correlation.
Hozumi, Hideaki*; Ogawa, Shuichi*; Yoshigoe, Akitaka; Ishizuka, Shinji*; Teraoka, Yuden; Takakuwa, Yuji*
no journal, ,
We investigated effects of lattice strain due to displacement of hetero atoms on a p-type Si(001) surface during oxidation. Experiments were performed using the surface reaction analysis apparatus placed at the BL23SU of SPring-8. In order to change the lattice strain, an SiC layer was formed by carbonization with CH exposure. Oxidation rate on the carbonized surface was faster than that on a clean surface. C1s photoemission intensity normalized by Si bulk intensity was almost constant during oxidation at the surface and gradually decreased at the interface. It was suggested that C atoms did not exist in the SiO layer and diffused into the Si substrate, and the growth of oxide was related with the normalized C1s intensity.
/Si interfacial oxidation, 1; Behavior of doped carbon atomHozumi, Hideaki*; Ogawa, Shuichi*; Yoshigoe, Akitaka; Ishizuka, Shinji*; Teraoka, Yuden; Takakuwa, Yuji*
no journal, ,
The oxidation reaction of SiC alloy layer which was formed with CH exposure on a p-type Si(001) surface is observed by real-time photoemission spectroscopy to investigate the role of lattice strain. Experiments were performed using the surface reaction analysis apparatus placed at the BL23SU of SPring-8. Oxidation rate on the SiC alloy layer was larger than that on a clean surface at interface oxidation. The number of carbon atom was constant for surface oxidation and reduced for interface oxidation suggesting that carbon atoms did not exist in the SiO layer and diffused into an Si substrate without CO or CO desorption during oxidation. Then, there was good correlation between the oxidation rate and the number of carbon atom. These results could be explained with the unified Si oxidation reaction model mediated by point defect generation.
/Si interfacial oxidation, 2; Carbon diffusion during 2D oxide island growthHozumi, Hideaki*; Ogawa, Shuichi*; Yoshigoe, Akitaka; Ishizuka, Shinji*; Harries, J.; Teraoka, Yuden; Takakuwa, Yuji*
no journal, ,
The oxidation reaction of SiC alloy layer which was formed with CH exposure on a p-type Si(001) surface was observed by real-time XPS to investigate the role of lattice strain. Experiments were performed using the surface reaction analysis apparatus placed at the BL23SU of SPring-8. When SiC alloy layer was oxidized at 660 C, oxidation mode was 2D oxide island growth. Etching advanced as well as oxidation films growth. Nearly 45 layers were etched for 7000 s from oxidation start regardless of oxide coverage was nearly 3 percents. This suggested SiO desorption occurred. In this result, SiC alloy layer that was formed on surface 4th layers should be completely rejected, but C 1s intensity that was normalized by Si 2p bulk intensity was constant. Therefore it was suggested carbon atoms diffused into Si substrate in SiO desorption.
C alloy layer/Si(001) surfacesHozumi, Hideaki*; Ogawa, Shuichi*; Yoshigoe, Akitaka; Ishizuka, Shinji*; Harries, J.; Teraoka, Yuden; Takakuwa, Yuji*
no journal, ,
In this study, to clarify the behavior of C on the basis of the oxidation kinetics, the oxidation kinetics of an SiC alloy layer was investigated by real-time photoelectron spectroscopy. The SiC alloy layer was formed by exposing an Si(001) surface to ethylene (CH). Although the solubility of C in an Si bulk is as small as about 3.5 
10
cm
, it is reported that the solubility of C can be increased by about 10
times due to the dimerization-induced strain. This makes it possible to form an SiC alloy layer on the Si(001) surface with x up to 0.2 but within only the first several Si layers. From a comparison between the changes in the depth profile of C and oxygen uptake, the enhancement of C diffusion is considered in terms of the oxidation-induced strain.
/Si interface during oxidation of SiC alloy layer on Si(001) surfacesHozumi, Hideaki*; Ogawa, Shuichi*; Yoshigoe, Akitaka; Ishizuka, Shinji*; Harries, J.; Teraoka, Yuden; Takakuwa, Yuji*
no journal, ,
The oxidation of SiC surface was studied by real-time X-ray photoelectron spectroscopy using synchrotron radiation to clarify the correlation between oxidation-induced strain and oxidation kinetics. Firstly, a p-type Si(001) surface was carbonized by CH. Then, the surface was oxidized at 773 K under 5.010
Pa of O. After saturation, the O pressure was increased to 1.310 Pa. Si-2p, O-1s, and C-1s photoelectron spectra were measured alternately during oxidation. From the time evolution of C-1s/Si-2p(Si
) ratio, it was found that the Si composes of bulk and strained Si atoms. The increase of C-1s/Si-2p(Si) ratio suggests the concentration of carbon at the interface. After O increase, the interface oxidation proceeds. The rate and the oxidation-induced strain decreased with oxidation. We concluded the interface oxidation rate is enhanced by oxidation-induced strain.
Hozumi, Hideaki*; Ogawa, Shuichi*; Yoshigoe, Akitaka; Ishizuka, Shinji*; Harries, J.; Teraoka, Yuden; Takakuwa, Yuji*
no journal, ,
The 3C-SiC formation on the Si(001) surface by ethylene has been studied. The facts that 3C-SiC nucleation takes place after incuvation time and four SiC alloy layers are formed during the incuvation time. In this study, critical carbon concentration for SiC nucleation has been investigated. Time evolution of Si2p and C1s photoemission peaks were observed by real-time synchrotron radiation photoemission spectroscopy during exposure Si(001) substrate to ethylene gas at 913 K. Consequently, 3C-SiC nucleation takes place at carbon concentration of 15%.
C alloy layers on Si(001) substrateHozumi, Hideaki*; Ogawa, Shuichi*; Yoshigoe, Akitaka; Ishizuka, Shinji*; Harries, J.; Teraoka, Yuden; Takakuwa, Yuji*
no journal, ,
Strained-Si channel complementary metal-oxide-semiconductor (CMOS) devices has been developed to improve the carrier mobility. In such CMOS devices, the channel layer is formed on an SiGe or by an SiC alloy layer. In the case of SiGe alloy layer, the oxidation of alloy layer is employed for Ge concentration. On the other hand, the detail of oxidation kinetics on the IV group alloy layer has not been cleared yet. In this study, the oxidation reaction kinetics on an SiC alloy layer was investigated by real-time X-ray photoelectron spectroscopy to reveal the oxidation rate and behavior of C atoms during oxidation.
/Si interfacial oxidation, 3; 3C-SiC growth caused by oxidation-induced carbon condensationHozumi, Hideaki*; Ogawa, Shuichi*; Yoshigoe, Akitaka; Ishizuka, Shinji*; Harries, J.; Teraoka, Yuden; Takakuwa, Yuji*
no journal, ,
An SiGe alloy layer is used for fabrication of strained Si-MOSFET devices. The use of C atoms instead of Ge is also presented. Oxidation processes in the gate insulator formation on the SiC alloy layer is completely different comparing to an Si clean surface. In this study, behavior of C atoms in the oxidation of SiC alloy layer has been investigated by real-time XPS. Concentration of C atoms in the SiO/Si interface took place due to induced strain by oxidation. And 3C-SiC growth occurred when C density increased over a critical value of 0.2.
