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Journal Articles

High reactivity of H$$_{2}$$O vapor on GaN surfaces

Sumiya, 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:6 Percentile:47.37(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 H$$_{2}$$O vapor has the highest reactivity due to the spin interaction between H$$_{2}$$O 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$$_{x}$$Ga$$_{1-x}$$N formation for p-GaN were observed at the interface of the Al$$_{2}$$O$$_{3}$$ layer deposited by ALD using H$$_{2}$$O vapor. This study suggests that an oxidant gas other than H$$_{2}$$O and O$$_{2}$$ should be used to avoid unintentional oxidation during Al$$_{x}$$Ga$$_{1-x}$$N atomi layer deposition.

Journal Articles

Comparison of heavy-ion transport simulations; Collision integral with pions and $$Delta$$ resonances in a box

Ono, Akira*; Xu, J.*; Colonna, M.*; Danielewicz, P.*; Ko, C. M.*; Tsang, M. B.*; Wang, Y,-J.*; Wolter, H.*; Zhang, Y.-X.*; Chen, L.-W.*; et al.

Physical Review C, 100(4), p.044617_1 - 044617_35, 2019/10

AA2019-0025.pdf:2.76MB

 Times Cited Count:67 Percentile:98.53(Physics, Nuclear)

International comparison of heavy-ion induced reaction models were discussed in the international conference "Transport2017" held in April 2017. Owing to their importance for safety assessment of heavy-ion accelerators and dosimetry of astronauts, various models to simulate heavy-ion induced reaction models are developed. This study is intended to clarify the difference among them to pinpoint their problems. In the comparison study, 320 protons and neutrons were packed in a 20-fm-large cube to calculate the number and energies of collisions during the time evolution. The author contributed to this study by running calculation using JQMD (JAERI Quantum Molecular Dynamics). This study showed that time step in the calculation is one of the biggest causes of the discrepancies. For example, the calculation by JQMD comprises 1-fm/c time steps, each of which is composed of transport, scattering and decay phases. Therefore a sequence of scattering, and decay followed by another scattering in 1 fm/c cannot be considered. Moreover, in JQMD particles are labeled by sequential numbers and scattering reactions are simulated by the order. Therefore scattering between low ID numbers, that between high ID numbers and that between the first (low ID) pair is overlooked in JQMD. Above indications obtained in this study must be kept in our mind for future JQMD upgrades.

Journal Articles

Comparison of heavy-ion transport simulations; Collision integral in a box

Zhang, Y.-X.*; Wang, Y,-J.*; Colonna, M.*; Danielewicz, P.*; Ono, Akira*; Tsang, M. B.*; Wolter, H.*; Xu, J.*; Chen, L.-W.*; Cozma, D.*; et al.

Physical Review C, 97(3), p.034625_1 - 034625_20, 2018/03

 Times Cited Count:110 Percentile:99.02(Physics, Nuclear)

International comparison of heavy-ion induced reaction models were discussed in the international conference "Transport2017" held in April 2017. Owing to their importance for safety assessment of heavy-ion accelerators and dosimetry of astronauts, various models to simulate heavy-ion induced reaction models are developed. This study is intended to clarify the difference among them to pinpoint their problems. In the comparison study, 320 protons and 320 neutrons were packed in a 20-fm-large cube to calculate the number of particle-particle collisions as well as the energies of collisions during the time evolution. In addition to the calculation, their algorithms were compared. The author contributed to this study by running calculation using JQMD (JAERI Quantum Molecular Dynamics). The results were compared with those calculated by the other 15 codes from over the world. Algorithm comparison showed that JQMD calculates collision probabilities from protons at first and collisions by neutrons are simulated later, which might be unreasonable. On the other hand, it was clarified that the calculation by JQMD agrees with those by the others. Despite the fact that some codes deviate from the average by a factor of 2, JQMD exhibited stable performance.

Journal Articles

Spectroscopy of $$^{153}$$Gd and $$^{157}$$Gd using the ($$p,d gamma$$) reaction

Ross, T. J.*; Hughes, R. O.*; Allmond, J. M.*; Beausang, C. W.*; Angell, C.; Basunia, M. S.*; Bleuel, D. L.*; Hurke, J. T.*; Casperson, R. J.*; Escher, J. E.*; et al.

Physical Review C, 90(4), p.044323_1 - 044323_12, 2014/10

 Times Cited Count:7 Percentile:45.81(Physics, Nuclear)

Journal Articles

Neutron spectroscopic factors of $$^{55}$$Ni hole-states from (p,d) transfer reactions

Sanetullaev, A.*; Tsang, M. B.*; Lynch, W. G.*; Lee, J.*; Bazin, D.*; Chan, K. P.*; Coupland, D.*; Hanzl, V.*; Hanzlova, D.*; Kilburn, M.*; et al.

Physics Letters B, 736, p.137 - 141, 2014/09

 Times Cited Count:16 Percentile:70.15(Astronomy & Astrophysics)

no abstracts in English

Journal Articles

Remnants of spherical shell structures in deformed nuclei; The Impact of an $$N$$ = 64 neutron subshell closure on the structure of $$N$$ $${approx}$$ 90 gadolinium nuclei

Ross, T. J.*; Hughes, R. O.*; Beausang, C. W.*; Allmond, J. M.*; Angell, C.; Basunia, M. S.*; Bleuel, D. L.*; Burke, J. T.*; Casperson, R. J.*; Escher, J. E.*; et al.

Physical Review C, 88(3), p.031301_1 - 031301_4, 2013/09

AA2013-0388.pdf:0.32MB

 Times Cited Count:7 Percentile:46.95(Physics, Nuclear)

Journal Articles

Spectroscopy of $$^{88}$$Y by the ($$p,dgamma$$) reaction

Ross, T. J.*; Beausang, C. W.*; Hughes, R. O.*; Scielzo, N. D.*; Burke, J. T.*; Allmond, J. M.*; Angell, C.; Basunia, M. S.*; Bleuel, D. L.*; Casperson, R. J.*; et al.

Physical Review C, 86(6), p.067301_1 - 067301_5, 2012/12

AA2012-0565.pdf:0.38MB

 Times Cited Count:3 Percentile:22.38(Physics, Nuclear)

Journal Articles

Measurement of the entry-spin distribution imparted to the high excitation continuum region of gadolinium nuclei via ($$p$$,$$d$$) and ($$p$$,$$t$$) reactions

Ross, T. J.*; Beausang, C. W.*; Hughes, R. O.*; Allmond, J. M.*; Angell, C.; Basunia, M. S.*; Bleuel, D. L.*; Burke, J. T.*; Casperson, R. J.*; Escher, J. E.*; et al.

Physical Review C, 85(5), p.051304_1 - 051304_5, 2012/05

AA2012-0155.pdf:0.62MB

 Times Cited Count:11 Percentile:52.69(Physics, Nuclear)

The surrogate reaction technique has been employed to $$(n,gamma)$$ cross sections in the actinide region to a precision of 20%, but in the rare earth region a factor of 2-3 discrepancy exists between the directly measured $$(n,gamma)$$ and extracted surrogate cross sections. A possible origin of this discrepancy lies in differences between the initial spin/parity population distribution. To investigate this, the angular momentum transfer of the surrogate reaction in Gd nuclei has been measured.

Journal Articles

History effects and phase diagram near the lower critical point in YBa$$_{2}$$Cu$$_{3}$$O$$_{7}$$ single crystals

Zhukov, A. A.*; de Groot, P. A. J.*; Kokkaliaris, S.*; Di Nicolo, E.*; Jansen, A. G. M.*; Mossang, E.*; Martinez, G.*; Wyder, P.*; Wolf, T.*; K$"u$pfer, H.*; et al.

Physical Review Letters, 87(1), p.017006_1 - 017006_4, 2001/07

 Times Cited Count:13 Percentile:59.95(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Thermohydromechanics of partially saturated geological media; Governing equations and formulation of four finite element codes

Sugita, Yutaka; Rutqvist, J.*; Noorisha, J.*; Tsang, C.-F.*; B$"o$rgesson, L.*; Nguyen, T. S.*

International Journal of Rock Mechanics and Mining Sciences, 38(1), p.105 - 127, 2001/00

None

Journal Articles

Coupled thermo-hydro-mechanical analysis of a heater test in fractured rock and bentonite at Kamaishi mine-comparison of field results to predictions of four finite element codes

Sugita, Yutaka; Rutqvist, J.*; B$"o$rgesson, L.*; Chijimatsu, Masakazu*; Nguyen, T. S.*; Jing, L.*; Noorisha, J.*; Tsang, C.-F.*

International Journal of Rock Mechanics and Mining Sciences, 38(1), p.129 - 142, 2001/00

no abstracts in English

Journal Articles

Transformations of the peak-effect near the multicritical point in YBa$$_{2}$$Cu$$_{3}$$Oy single crystals

Zhukov, A. A.*; Kokkaliaris, S.*; de Groot, P. A. J.*; Jansen, A. G. M.*; Mossang, E.*; Asaoka, Hidehito; Wolf, T.*; Gagnon, R.*; Taillefer, L.*

Physica C, 341-348(Part2), p.1027 - 1030, 2000/11

no abstracts in English

Oral presentation

In-situ observation of oxidation on GaN surface by real-time XPS under irradiating oxidation gas

Sumiya, Masatomo*; Tsuda, Yasutaka; Sakamoto, Tetsuya*; Sumita, Masato*; Sang, L.*; Harada, Yoshitomo*; Yoshigoe, Akitaka

no journal, , 

no abstracts in English

13 (Records 1-13 displayed on this page)
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