Measurement of ion beam induced current in quantum dot solar cells

Nakamura, Tetsuya*; Imaizumi, Mitsuru*; Sato, Shinichiro; Sugaya, Takeyoshi*; Mochizuki, Toru*; Okano, Yoshinobu*; Oshima, Takeshi

Proceedings of 11th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-11) (Internet), p.73 - 76, 2015/11

The radiation effect on GaAs p-i-n solar cells with quantum dot (QD) in the i-layer was investigated. In a previous work, we particularly noted the degradation of fill-factor (FF) for the QD cells. In this work, to clarify the reason of the FF degradation in QD cells, generation current due to low-energy proton irradiation, which we call ion beam induced current (IBIC), was observed to characterize behavior of the generated minority carrier by the protons in the depletion region where QDs are located. The energy of protons was adjusted to damage the depletion region, and decrease of generation current was measured during the proton irradiation. The results suggest that the serious degradation of FF is caused by a decrease of the carrier collection efficiency in the depletion region due to proton damage.

On the electronic structures of Th and Ac hydrate models

Mochizuki, Yuji*; Tsushima, Satoru*

Chemical Physics Letters, 372(1-2), p.114 - 120, 2003/04

https://doi.org/10.1016/S0009-2614(03)00373-7

no abstracts in English

Large-scaled thermohydraulic tests plan for cooling systems in fast reactors; Experimental models of reactor vessel and the primary cooling system

Kamide, Hideki; Hayashi, Kenji; Gunji, Minoru; Hayashida, Hitoshi; Nishimura, Motohiko; Iitsuka, Toru; Kimura, Nobuyuki; Tanaka, Masaaki; Nakai, Satoru; Mochizuki, Hiroyasu; et al.

PNC TN9410 96-279, 51 Pages, 1996/08

PNC-TN9410-96-279.pdf:2.92MB

Large-scaled thermohydraulic tests are planned for some new key technologies in the heat transport systems of demonstration fast reactors, in which the reactor vessel, the primary system, the secondary system, water-steam system, and the decay heat removal systems are modeled. Thermohydraulic issues and structural integrity issues were discussed for the top entry piping systems with satellite pools of the intermediate heat exchangers and the pumps, the natural circulation decay heat removal using direct heat exchangers in a reactor hot pool, the reactor vessel wall cooling system, and the new type of steam generators in the demonstration reactor. Concepts of the experimental model for the reactor vessel and the primary system were created and compared with each other for the sodium test facility which enables to answer the thermohydraulic and structural integrity issues. Following items were considered in the creation and in the selection of the models; (1)solution of the issues for Demonstration First Reactor on total system characteristics, the reactor vessel wall cooling system, the decay heat removal system, and the steam generator, (2)balance between the thermohydraulic issues and the structural integrity issues, (3)simulations of compound phenomena and interactions between the components and the heat transport systems. Total system of test facility was specified based on the selected test model.

Investigation of microbiologically influenced corrosion inhibition of carbon steel in compacted bentonite under subsurface environment

Nagaoka, Toru*; Hirano, Shinichi*; Kosaba, Takumi*; Amano, Yuki; Mochizuki, Akihito

no journal, , 

In-situ corrosion experiment of carbon steel coupons embedded in compacted bentonite were conducted in the subsurface environment at the Horonobe underground Research Laboratory. The experiment was carried out at the 250 m depth using boreholes. To simulate a small schale of geological disposal condition, compacted bentonite coupons in the test cells were made of 100% bentonite material (Kunigel V1) with different dry densities (1.0, 1.4, 1.6, 1.8 g/cm). After the installation, the test cells were collected after a certein period of time and measured the number of viable bacteria and analyzed microbial community stracture based on 16S rRNA gene. The carbon steel coupons were subjected to weight impairment measurements and analysis of corrosion products. The results showed that the weight of carbon steel coupons in compacted bentonite decreased at all conditions, but the amount of weight-loss tended to be greater at lower dry densities. The weight-loss was particularly large at the lowest dry density of 1.0 g/cm, and corrosion was suppressed at dry densities of 1.4 g/cm and higher. The corrosion rate tended to decrease in the later stages of the test compared to the early stages of the test. To evaluate the effect of microorganisms on the corrosion behavior, the number of viable bacteria in the collected bentonite samples was measured. The results showed that the number of aerobic bacteria tended to decrease with increasing dry density. In addition, 16S rRNA gene analysis showed that the composition of the microflora at high drying density was similar to that in the initial bentonite, while the microflora at low drying density was significantly altered. These findings suggest that microorganisms may be active in compacted bentonite at low dry density and promote corrosion.

Radiation response of fill-factor for GaAs solar cells with InGaAs quantum dot layers

Nakamura, Tetsuya*; Sumita, Taishi*; Imaizumi, Mitsuru*; Sugaya, Takeyoshi*; Matsubara, Koji*; Niki, Shigeru*; Mochizuki, Toru*; Takeda, Akihiro*; Okano, Yoshinobu*; Sato, Shinichiro; et al.

no journal, , 

Radiation effects on GaAs solar cells with InGaAs dot layers were investigated in order to consider the capability of them for space applications. The GaAs solar cells with 50 InGaAs dot layers and also GaAs solar cells with no dot layer were fabricated using a MBE method. They were irradiated with 150 keV-protons at room temperature. As a result, solar cell with dot layers showed higher radiation degradation in short circuit current however, lower degradation in open circuit voltage. Since no significant difference in the degradation of current - voltage characteristics under dark conditions between dot and non-dot solar cells, it is concluded that the degradation of fill fuctor does not come from the degradation of pn diode characteristics but might come from the degradation of minority carrier diffusion length.

In-situ observation of radiation degradation of GaAs solar cells with InGaAs quantum dot layers

Oshima, Takeshi; Nakamura, Tetsuya*; Sugaya, Takeyoshi*; Sumita, Taishi*; Imaizumi, Mitsuru*; Sato, Shinichiro; Matsubara, Koji*; Niki, Shigeru*; Mochizuki, Toru*; Takeda, Akihiro*; et al.

no journal, , 

Changes in the dynamics of human -synuclein detected by neutron scattering

Fujiwara, Satoru; Araki, Katsuya*; Matsuo, Tatsuhito; Yagi, Hisashi*; Yamada, Takeshi*; Shibata, Kaoru; Mochizuki, Hideki*

no journal, ,