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Journal Articles

Charge generated in 6H-SiC n$$^{+}$$p diodes by MeV range heavy ions

Oshima, Takeshi; Iwamoto, Naoya; Onoda, Shinobu; Wagner, G.*; Ito, Hisayoshi; Kawano, Katsuyasu*

Surface & Coatings Technology, 206(5), p.864 - 868, 2011/11

 Times Cited Count:4 Percentile:19.09(Materials Science, Coatings & Films)

Charge induced in n$$^{+}$$p Silicon Carbide (6H-SiC) diodes by heavy ions, oxygen (O), silicon (Si), nickel (Ni), and gold (Au) using a Transient Ion Beam Induced Current (TIBIC) measurement system. The slight increase in collected charge shows in a low bias region, and then, the values are saturated in a high bias region. This indicates that in the low bias region, since the length of the depletion layer is shorter than the ion range, carriers induced in deeper than the depletion layer diffuse and annihilate before they reach the depletion layer. Since the length of the depletion layer increases with increasing bias voltage, the charge collected by diodes increases with increasing bias voltage. In the case of the high bias, the length of the depletion layer is longer than the ion range. As a result, all carriers are induced in the depletion layer, and they can be collected by the electric field. Thus, This indicates that the value of collected charge does not depend on bias voltage. From the point of view of charge collection efficiency (CCE), the collected charge decrease with increasing atomic number. From the calculation, it is found that dense electron-hole pairs were generated in SiC by irradiation of ions with heavy mass. The decrease in the CCE due to ion irradiation with heavy mass can be interpreted in terms of the annihilation of e-h pairs in plasma due to the Auger recombination.

Journal Articles

Transient response of charge collection by single ion strike in 4H-SiC MESFETs

Onoda, Shinobu; Iwamoto, Naoya; Ono, Shuichi*; Katakami, Shuji*; Arai, Manabu*; Kawano, Katsuyasu*; Oshima, Takeshi

IEEE Transactions on Nuclear Science, 56(6), p.3218 - 3222, 2009/12

 Times Cited Count:18 Percentile:74.84(Engineering, Electrical & Electronic)

no abstracts in English

Journal Articles

Comparative study of transient current induced in SiC p$$^{+}$$n and n$$^{+}$$p diodes by heavy ion micro beams

Oshima, Takeshi; Iwamoto, Naoya; Onoda, Shinobu; Kamiya, Tomihiro; Kawano, Katsuyasu*

Nuclear Instruments and Methods in Physics Research B, 267(12-13), p.2189 - 2192, 2009/06

 Times Cited Count:9 Percentile:53.56(Instruments & Instrumentation)

In this study, p$$^{+}$$n and n$$^{+}$$p diodes were fabricated on 6H-SiC epitaxial layers. The transient currents induced in these diodes by the incidence of tens MeV range heavy ion micro beams were collected by the Transient Ion Beam Induced Current (TIBIC) measurement system. The value of Charge Collection Efficiency (CCE) for the SiC diodes was obtained by analyzing the transient currents. As a result using 9 MeV-oxygen ions, the CCE value of around 85 % was obtained from both p$$^{+}$$n and n$$^{+}$$p diodes. Since the CCE value includes non-ionizing energy loss as well as the decay of charge in the measurement system, the obtained CCE value suggests that SiC p$$^{+}$$n as well as n$$^{+}$$p diodes are suitable for particle detectors. For ion species dependence, the values of CCE for both p$$^{+}$$n and n$$^{+}$$p diodes decrease with increasing atomic number of incident ions. This decrease in CCE by heavy ion incidence can be interpreted in terms of Auger recombination in dense electron-hole pairs.

Journal Articles

Degradation modeling of InGaP/GaAs/Ge triple-junction solar cells irradiated with various-energy protons

Sato, Shinichiro; Miyamoto, Haruki*; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Morioka, Chiharu*; Kawano, Katsuyasu*; Oshima, Takeshi

Solar Energy Materials and Solar Cells, 93(6-7), p.768 - 773, 2009/06

 Times Cited Count:71 Percentile:90.69(Energy & Fuels)

Degradation modeling of InGaP/GaAs/Ge triple-junction (3J) solar cells subjected to proton irradiation is performed with the use of a one-dimensional optical device simulator, PC1D. By fitting the external quantum efficiencies of 3J solar cells degraded by 30 keV, 150 keV, 3 MeV, or 10 MeV protons, the shortcircuit currents ($$I_{SC}$$) and open-circuit voltages ($$V_{OC}$$) are simulated. The damage coefficients of minority carrier diffusion length ($$K_L$$) and the carrier removal rate of base carrier concentration ($$R_C$$) of each subcell are also estimated. The values of $$I_{SC}$$ and $$V_{OC}$$ obtained from the calculations show good agreement with experimental values at an accuracy of 5%. These results confirm that the degradation modeling method developed in this study is effective for the lifetime prediction of 3J solar cells.

Journal Articles

Reduction of effective carrier density and charge collection efficiency in SiC devices due to radiations

Onoda, Shinobu; Iwamoto, Naoya; Hirao, Toshio; Kawano, Katsuyasu*; Kojima, Kazutoshi*; Oshima, Takeshi

AIP Conference Proceedings 1099, p.1010 - 1013, 2009/03

no abstracts in English

Journal Articles

Estimation of diffusion length by using heavy ion microbeam

Onoda, Shinobu; Iwamoto, Naoya; Hirao, Toshio; Oshima, Takeshi; Kawano, Katsuyasu*

JAEA-Conf 2008-012, p.146 - 149, 2009/03

no abstracts in English

Journal Articles

Transient response to high energy heavy ions in 6H-SiC n$$^+$$p diodes

Onoda, Shinobu; Oshima, Takeshi; Hirao, Toshio; Hishiki, Shigeomi; Iwamoto, Naoya; Kojima, Kazutoshi*; Kawano, Katsuyasu*

Materials Science Forum, 600-603, p.1039 - 1042, 2009/00

no abstracts in English

Journal Articles

Degradation of charge collection efficiency for 6H-SiC diodes by electron irradiation

Iwamoto, Naoya; Onoda, Shinobu; Hishiki, Shigeomi; Oshima, Takeshi; Murakami, Makoto*; Nakano, Itsuo*; Kawano, Katsuyasu*

Materials Science Forum, 600-603(Part 2), p.1043 - 1046, 2009/00

The 6H-SiC n$$^{+}$$p diodes were fabricated on a p-type substrate. To clarify the radiation resistance of the device performance, the diodes were irradiated with 1MeV-electrons at fluence up to 6$$times$$10$$^{16}$$/cm$$^{2}$$ and the Charge Collection Efficiencies (CCEs) and diffusion length (L) of minority carriers were evaluated from the evaluation of the Transient Ion Beam Induced Current (TIBIC). The saturated CCE of 93% was obtained for non-electron irradiated diodes, and the value of CCE was kept up to electron fluences of 1$$times$$10$$^{15}$$/cm$$^{2}$$, although L decreased to 0.6$$mu$$m from 2.5$$mu$$m by the irradiation. The degradation of CCE was observed at fluences above 5$$times$$10$$^{15}$$/cm$$^{2}$$.

Journal Articles

Effects of fabrication process on the electrical characteristics of n-channel MOSFETs irradiated with gamma-rays

Hishiki, Shigeomi; Iwamoto, Naoya; Oshima, Takeshi; Ito, Hisayoshi; Kojima, Kazutoshi*; Kawano, Katsuyasu*

Materials Science Forum, 600-603, p.707 - 710, 2009/00

The n-channel 6H-SiC MOSFETs were fabricated using different process. The carbon-coated MOSFETs showed higher radiation resistance than non-coated ones. The generation of interface traps for carbon-coated MOSFETs was smaller than that for non-coated MOSFETs. This origin can be interptered in terms of the surface degradation by thermal annealing process after ion implantation.

Journal Articles

Charge collection properties of 6H-SiC diodes by wide variety of charged particles up to several hundreds MeV

Onoda, Shinobu; Iwamoto, Naoya; Murakami, Makoto; Oshima, Takeshi; Hirao, Toshio; Kojima, Kazutoshi*; Kawano, Katsuyasu*; Nakano, Itsuo*

Materials Science Forum, 615-617, p.861 - 864, 2009/00

no abstracts in English

Journal Articles

Transient currents induced in 6H-SiC MOS capacitors by oxygen ion incidence

Iwamoto, Naoya; Onoda, Shinobu; Oshima, Takeshi; Kojima, Kazutoshi*; Kawano, Katsuyasu*

Materials Science Forum, 615-617, p.517 - 520, 2009/00

Single event transient currents induced in 6H-SiC Metal-Oxide-Semiconductors (MOS) capacitors by using oxygen ions are investigated. Charges collected from the MOS capacitors are estimated by the integration of transient currents. Applying the drift-diffusion model to the collected charges, the diffusion length of electron is estimated. Transient currents induced in the $$gamma$$-ray irradiated MOS capacitors are also investigated. No significant change in the transient currents is observed after $$gamma$$-ray irradiation.

Journal Articles

NIEL analysis of charge collection efficiency in silicon carbide diodes damaged by gamma-rays, electrons and protons

Oshima, Takeshi; Onoda, Shinobu; Iwamoto, Naoya; Kojima, Kazutoshi*; Kawano, Katsuyasu*

Proceedings of the 8th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-8), p.175 - 178, 2008/12

The reduction of Charge Collection Efficiency (CCE) in silicon carbide (SiC) diodes due to $$gamma$$-ray, 1MeV electron, and 65MeV proton irradiations is discussed. The pn junction diodes were fabricated on SiC epitaxial layers using hot implantation. The transient currents induced by ion beam were measured using Transient Ion Beam Induced Current (TIBIC) measurement systems. The CCE are estimated from the integration of the transient current. The diodes were irradiated with either $$gamma$$-rays, electrons at 1MeV, or protons at 65 MeV to create damage in the diodes. The CCE in the irradiated diodes was also measured. The results obtained in these measurements were evaluated using a concept of Non Ionizing Energy Loss (NIEL).

Journal Articles

Charge collection from SiC MOS capacitors irradiated with oxygen ion

Iwamoto, Naoya; Onoda, Shinobu; Oshima, Takeshi; Kojima, Kazutoshi*; Kawano, Katsuyasu*

Proceedings of the 8th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-8), p.191 - 194, 2008/12

no abstracts in English

Journal Articles

NIEL analysis of radiation degradation parameters derived from quantum efficiency of triple-junction space solar cell

Sato, Shinichiro; Miyamoto, Haruki; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Morioka, Chiharu*; Kawano, Katsuyasu*; Oshima, Takeshi

Proceedings of 33rd IEEE Photovoltaic Specialists Conference (PVSC-33) (CD-ROM), 5 Pages, 2008/00

Degradation modeling of InGaP/GaAs/Ge triple-junction (3J) solar cells due to proton irradiation is performed with the use of a one-dimensional optical device simulator; PC1D, and the degradation level in each sub-cell is evaluated. By fitting external quantum efficiencies of the 3J solar cells degraded by proton irradiation, the short-circuit currents ($$I_{SC}$$) and open-circuit voltages ($$V_{OC}$$) are simulated. The validity of this model is confirmed by comparing the results of both $$I_{SC}$$ and $$V_{OC}$$ to the experimental data. The carrier removal rate of base layer ($$R_C$$) and the damage coefficient of minority carrier diffusion length ($$K_L$$) in each sub-cell are also estimated. In addition, NIEL (Non-Ionizing Energy Loss) analysis for both radiation degradation parameters $$K_L$$ and $$R_C$$ is discussed.

Journal Articles

Decrease of charge collection due to displacement damage by $$gamma$$ rays in a 6H-SiC diode

Onoda, Shinobu; Oshima, Takeshi; Hirao, Toshio; Mishima, Kenta; Hishiki, Shigeomi; Iwamoto, Naoya; Kojima, Kazutoshi*; Kawano, Katsuyasu*

IEEE Transactions on Nuclear Science, 54(6), p.1953 - 1960, 2007/12

 Times Cited Count:18 Percentile:76.94(Engineering, Electrical & Electronic)

Journal Articles

Impact of Auger recombination on charge collection of a 6H-SiC diode by heavy ions

Onoda, Shinobu; Oshima, Takeshi; Hirao, Toshio; Mishima, Kenta; Hishiki, Shigeomi; Iwamoto, Naoya; Kawano, Katsuyasu*

IEEE Transactions on Nuclear Science, 54(6), p.2706 - 2713, 2007/12

 Times Cited Count:16 Percentile:72.08(Engineering, Electrical & Electronic)

no abstracts in English

Journal Articles

Degradation modeling of InGaP/GaAs/Ge triple junction solar cells irradiated with various energy protons

Sato, Shinichiro; Miyamoto, Haruki; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Morioka, Chiharu*; Kawano, Katsuyasu*; Oshima, Takeshi

Proceedings of 17th International Photovoltaic Science and Engineering Conference (PVSEC-17) (CD-ROM), p.502 - 503, 2007/12

Degradation modeling of InGaP/GaAs/Ge triple junction (3J) solar cells with the use of a one dimensional optical device simulator, PC1D, is performed for cell lifetime prediction. By fitting the quantum efficiencies of 3J solar cells degraded by 30 keV, 150 keV, 3 MeV, or 10 MeV proton irradiation, the short circuit currents (Isc) and open circuit voltages (Voc) are simulated. The damage coefficient of minority carrier diffusion length ($$K_L$$) and carrier removal rate ($$R_C$$) of base carrier concentration of each sub cell are also estimated. The values of Isc and Voc obtained using the calculations show good agreement with experimental values. These results confirm that the degradation modeling method is effective for lifetime prediction of 3J solar cells.

Journal Articles

Effects of irradiation temperature on degradation of electrical characteristics of InGaP solar cells

Miyamoto, Haruki; Sato, Shinichiro; Oshima, Takeshi; Morioka, Chiharu*; Imaizumi, Mitsuru*; Kawano, Katsuyasu*

Proceedings of 17th International Photovoltaic Science and Engineering Conference (PVSEC-17) (CD-ROM), p.961 - 962, 2007/12

InGaP and Si solar cells are irradiated with 10 MeV protons at fluences up to $$1 times 10^{13}$$ cm$$^{-2}$$ at room temperature (RT) and low temperature (LT). Results show that the remaining factor Voc irradiated at LT is higher than that at RT, and vice versa for Isc. The temperature coefficient of Voc after irradiation is greater than that before irradiation, although the coefficients of Isc are the same before and after irradiation. This degradation of the output performance of these solar cells can be interpreted in terms of a decrease in minority-carrier diffusion length.

Journal Articles

Reconsideration of electron irradiation test methods for the evaluation of space solar cells

Oshima, Takeshi; Sato, Shinichiro; Miyamoto, Haruki; Imaizumi, Mitsuru*; Hanaya, Hiroaki; Kawano, Katsuyasu*

Proceedings of 17th International Photovoltaic Science and Engineering Conference (PVSEC-17) (CD-ROM), p.955 - 956, 2007/12

In this study, we reconsider electron irradiation methods for the evaluation of radiation response of space solar cells. We show irradiation test methods performed at JAEA, such as a sequential method, in which the electrical performance of solar cells is measured outside of an irradiation facility after irradiation, and a simultaneous method, in which the electrical performance of solar cells can be measured in-situ. The results obtained from the sequential method are compared to these obtained from the simultaneous method. The reasonable distance between samples and the accelerator window to take reliable data on the basis of the energy decay of electrons by atmosphere is also discussed.

Journal Articles

Decrease in ion beam induced charge of 6H-SiC diodes

Onoda, Shinobu; Iwamoto, Naoya; Oshima, Takeshi; Hirao, Toshio; Kawano, Katsuyasu*

Proceedings of the 26th Symposium on Materials Science and Engineering, Research Center of Ion Beam Technology Hosei University, p.35 - 40, 2007/12

no abstracts in English

65 (Records 1-20 displayed on this page)