Single event gate rupture in SiC MOS capacitors with different gate oxide thicknesses

Deki, Manato*; Makino, Takahiro; Kojima, Kazutoshi*; Tomita, Takuro*; Oshima, Takeshi

Materials Science Forum, 778-780, p.440 - 443, 2014/02

https://doi.org/10.4028/www.scientific.net/MSF.778-780.440

no abstracts in English

Breakdown voltage in silicon carbide metal-oxide-semiconductor devices induced by ion beams

Oshima, Takeshi; Deki, Manato; Makino, Takahiro; Iwamoto, Naoya; Onoda, Shinobu; Hirao, Toshio*; Kojima, Kazutoshi*; Tomita, Takuro*; Matsuo, Shigeki*; Hashimoto, Shuichi*

AIP Conference Proceedings 1525, p.654 - 658, 2013/04

https://doi.org/10.1063/1.4802408

Metal-Oxide-Semiconductor (MOS) capacitors were fabricated on n-type 4H-SiC epitaxial layers, and the leakage current through the gate oxide during heavy ion irradiation was investigated in order to evaluate dielectric breakdown induced by heavy ions (Single Event Gate Rupture: SEGR). The gate oxide at thickness ranges between 60 and 80 nm was formed using pyrogenic oxidation at 1100 C for 60 min. Circular electrodes with 180 diameter were formed using Al evaporation and a lift-off technique. The leakage current observed through the gate oxide was monitored during 18 MeV oxygen (O) or nickel (Ni) ions. As a result, although no significant difference in the value of the electric field at the dielectric breakdown (around 8.2 MV/cm) was observed between non-irradiated and 18 MeV-O irradiated samples, the value decreased to be 7.3 MV/cm in the case of 18 MeV-Ni ion incidence. The Linier Energy Transfer (LET) for 18 MeV-O is 7 MeV cm/mg, and this value is smaller than that for 18 MeV-Ni (24 MeV cm/mg). Also, 18 MeV-Ni ions deposit energy in narrower regions than 18 MeV-O ions. Thus, it can be concluded that the high density of charge induced by 18 MeV-Ni ions triggers SEGR in SiC MOS capacitors.

LET dependence of gate oxide breakdown of SiC-MOS capacitors due to single heavy ion irradiation

Deki, Manato; Makino, Takahiro; Tomita, Takuro*; Hashimoto, Shuichi*; Kojima, Kazutoshi*; Oshima, Takeshi

Proceedings of 10th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-10) (Internet), p.78 - 81, 2012/12

Metal-Oxide-Semiconductor (MOS) capacitors fabricated on Silicon Carbide (SiC) under applied biases were irradiated with heavy ions. The relationship between critical electric field (E) and Linear Energy Transfer (LET) was investigated. As a results of 9 MeV-Ni, 18 MeV-Ni, Kr-322 MeV and 454 MeV-Xeirradiation (the values of LET are 14.6, 23.8, 42.2 and 73.2 MeV cm/mg, respectively), reciprocal value of E increases with increasing LET. The similar relationship was also reported Si MOS capacitors. However, the increase in SiC MOS capacitors is smaller than that in Si ones because the generation energy of one electron-hole pair for SiC is larger than that for Si.

Refreshable decrease in peak height of ion beam induced transient current from silicon carbide metal-oxide-semiconductor capacitors

Oshima, Takeshi; Iwamoto, Naoya; Onoda, Shinobu; Makino, Takahiro; Deki, Manato; Nozaki, Shinji*

AIP Conference Proceedings 1336, p.660 - 664, 2011/05

https://doi.org/10.1063/1.3586184

Metal-Oxide-Semiconductor (MOS) capacitors were fabricated on n-type 4H- and 6H-SiC epitaxial layers, and transient currents induced in SiC MOS capacitors by ion incidence were investigated. Transient Ion Beam Induced Current (TIBIC) measurements were performed using 15 MeV oxygen ions. As a result, the TIBIC peak height decreased with increasing number of incident ions. For example, the TIBIC signal peak for a 4H-SiC MOS capacitor at a reverse bias of 15 V was 0.18 mA at the beginning. The peak decreased to be 0.10 mA after 1800 ion irradiation. After that, the forward bias of 1 V was applied to the MOS capacitor and the TIBIC measurements were carried out under the same conditions. As a result, the peak height was recovered to be 0.18 mA. In general, the response of charge de-trapping by deep levels in wide bandgap semiconductors is very slow and they act as fixed charge. Since dense electron-hole pairs are generated by ion incident and holes move to the SiO/SiC interface by the electric field (applied reverse bias). Therefore, the decrease in TIBIC signal peak can be interpreted in terms of the recombination of negatively charged acceptor type deep levels with ion induced holes.

Laser modification aiming at the enhancement of local electrical conductivities in SiC

Deki, Manato; Ito, Takuto*; Tomita, Takuro*; Matsuo, Shigeki*; Hashimoto, Shuichi*; Kitada, Takahiro*; Isu, Toshiro*; Onoda, Shinobu; Oshima, Takeshi

Proceedings of 9th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-9), p.218 - 221, 2010/10

Single-shot picosecond interferometry with one-nanometer resolution for dynamical surface morphology using a soft X-ray laser

Suemoto, Toru; Terakawa, Kota*; Ochi, Yoshihiro; Tomita, Takuro*; Yamamoto, Minoru; Hasegawa, Noboru; Deki, Manato*; Minami, Yasuo*; Kawachi, Tetsuya

Optics Express (Internet), 18(13), p.14114 - 14122, 2010/06

https://doi.org/10.1364/OE.18.014114

Using highly coherent radiation at a wavelength of 13.9 nm from a Ag-plasma soft X-ray laser, we constructed a pump-and-probe interferometer based on a double Lloyd's mirror system. The spatial resolutions are evaluated with a test pattern, showing 1.8 micrometers lateral resolution, and 1-nm depth sensitivity. This instrument enables a single-shot observation of the surface morphology with a 7-ps time-resolution. We succeeded in observing a nanometer scale surface dilation of Pt films at the early stage of the ablation process initiated by a 70 fs near infrared pump pulse.

Femtosecond laser modification aiming at the enhancement of local electric conductivities on SiC

Deki, Manato; Yamamoto, Minoru*; Ito, Takuto*; Tomita, Takuro*; Matsuo, Shigeki*; Hashimoto, Shuichi*; Kitada, Takahiro*; Isu, Toshiro*; Onoda, Shinobu; Oshima, Takeshi

no journal, , 

no abstracts in English

Polarization dependence of local electric conductivities in femtosecond laser modified SiC

Ito, Takuto*; Deki, Manato; Tomita, Takuro*; Matsuo, Shigeki*; Hashimoto, Shuichi*; Kitada, Takahiro*; Isu, Toshiro*; Onoda, Shinobu; Oshima, Takeshi

no journal, , 

no abstracts in English

Unusual charge collection from 4H-SiC Schottky barrier diode

Makino, Takahiro; Deki, Manato; Iwamoto, Naoya; Onoda, Shinobu; Hoshino, Norihiro*; Tsuchida, Hidekazu*; Oshima, Takeshi

no journal, , 

no abstracts in English

Pulse fluence dependence of local electrical conductivities in femtosecond laser modified SiC

Deki, Manato; Ito, Takuto*; Tomita, Takuro*; Matsuo, Shigeki*; Hashimoto, Shuichi*; Kitada, Takahiro*; Isu, Toshiro*; Onoda, Shinobu; Oshima, Takeshi

no journal, , 

no abstracts in English