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Journal Articles

Anharmonic vibrations of the dicarbon antisite defect in 4H-SiC

Yan, F.*; Devaty, R. P.*; Choyke, W. J.*; Gali, A.*; Kimoto, Tsunenobu*; Oshima, Takeshi; Pensl, G.*

Applied Physics Letters, 100(13), p.132107_1 - 132107_3, 2012/03

 Times Cited Count:2 Percentile:10.01(Physics, Applied)

Journal Articles

Deep defects in 3C-SiC generated by H$$^{+}$$- and He$$^{+}$$-implantation or by irradiation with high-energy electrons

Weidner, M.*; Trapaidze, L.*; Pensl, G.*; Reshanov, S. A.*; Sch$"o$ner, A.*; Ito, Hisayoshi; Oshima, Takeshi; Kimoto, Tsunenobu*

Materials Science Forum, 645-648, p.439 - 442, 2010/00

Intrinsic defects in 3C-SiC generated by implantation of H$$^{+}$$ and He$$^{+}$$ ions or by irradiation of high energy electrons were investigated using DLTS (Deep Level Transient Spectroscopy). The defect parameters and the thermal stability of the observed defects are determined. The dominant DLTS peak was named W6-center and its capture-cross-section was directly measured by variation of the filling pulse length. The charge state of the W6-center is obtained from double-correlated DLTS investigations according to the Poole-Frenkel effect.

Journal Articles

Thermal stability of defects centers in n- and p-type 4H-SiC epilayers generated by irradiation with high-energy electrons

Reshanov, S. A.*; Beljakowa, S.*; Zippelius, B.*; Pensl, G.*; Danno, K.*; Alfieri, G.*; Kimoto, Tsunenobu*; Onoda, Shinobu; Oshima, Takeshi; Yan, F.*; et al.

Materials Science Forum, 645-648, p.423 - 426, 2010/00

n- and p-type 4H-SiC epilayers were irradiated with electrons at 170 keV or 1 MeV. Subsequent annealing (in Ar, 30 min) up to 1700 $$^{circ}$$C was carried out. Defects in the samples were investigated using DLTS (Deep Level Transient Spectroscopy). As a results, for n-type, dominant defects were Z1/Z2 and EH7, and they can observed for both 170 keV- and 1 MeV-irradiated samples. Both defects decreased with increasing temperature up to 1100 $$^{circ}$$C, although they appeared again at 1400 $$^{circ}$$C. Then they disappeared at 1600 $$^{circ}$$C. For p-type, defects named UK1 and HK2 were observed and they were very stable. No significant decrease was observed after 1700 $$^{circ}$$C annealing.

Journal Articles

Thermal histories of defect centers as measured by low temperature photoluminescence in n- and p-type 4H SiC epilayers generated by irradiation with 170 KeV or 1 MeV electrons

Yan, F.*; Devaty, R. P.*; Choyke, W. J.*; Danno, Katsunori*; Alfieri, G.*; Kimoto, Tsunenobu*; Onoda, Shinobu; Oshima, Takeshi; Reshanov, S. A.*; Beljakowa, S.*; et al.

Materials Science Forum, 645-648, p.419 - 422, 2010/00

Defects in n- and p-type 4H-SiC epitaxial layer were investigated by low temperature photoluminescence spectroscopy (LTPL) and deep level transient spectroscopy (DLTS). Defects were introduced by either 170 keV or 1 MeV electron irradiation into samples at RT. The samples were annealed from 25$$^{circ}$$C to 1700$$^{circ}$$C in 100$$^{circ}$$C steps. As a result of LTPL measurements, L$$_{1}$$ line was observed after irradiation. In previous studies, L$$_{1}$$ line is thought to correlate with Z$$_{1}$$/Z$$_{2}$$ centers in DLTS measurements. However, in this study, no correlation between L$$_{1}$$ and Z$$_{1}$$1/Z$$_{2}$$ was observed.

Journal Articles

New lines and issues associated with deep defect spectra in electron, proton and $$^{4}$$He ion irradiated 4H SiC

Yan, F.*; Devaty, R. P.*; Choyke, W. J.*; Kimoto, Tsunenobu*; Oshima, Takeshi; Pensl, G.*; Gali, A.*

Materials Science Forum, 645-648, p.411 - 414, 2010/00

Silicon Carbide (SiC) samples were irradiated with electron, proton and $$^{4}$$He ions and defects in the irradiated SiC were investigated by Low Temperature Photo Luminescence (LTPL). After irradiation, PL spectra between 2.48 and 2.62 eV were measured at 7 K. As a results, several PL lines were observed. These lines showed the same annealing behavior and were annealed out between 1300 and 1400$$^{circ}$$C. Therefore, it is concluded that these line have the same origin. In addition, as a result of simulation, the structure of the defect is determined to be di-carbon antisite.

Journal Articles

Shallow defects observed in as-grown and electron-irradiated or He$$^{+}$$-implnated Al-doped 4H-SiC epilayers

Beljakowa, S.*; Reshanov, S. A.*; Zippelius, B.*; Krieger, M.*; Pensl, G.*; Danno, Katsunori*; Kimoto, Tsunenobu*; Onoda, Shinobu; Oshima, Takeshi; Yan, F.*; et al.

Materials Science Forum, 645-648, p.427 - 430, 2010/00

Defects in Al-doped p-type 4H-SiC were investigated using admittance spectroscopy (AS). Also, defects in 4H-SiC irradiated with electrons and He ions were studied using AS. As a result, a shallow level with activation energy at 170 meV was found and is has the capture cross section of 3.5$$times$$10$$^{-16}$$/cm$$^{2}$$ which is extremely low value. The concentration of the defect did not change even after electron and He irradiations. Also, the defect can be found after annealing at 1800 $$^{circ}$$C. Therefore, we can conclude that the defect is a very stable intrinsic defect in SiC.

Journal Articles

Reduction of interface traps and enhancement of channel mobility in n-channel 6H-SiC MOSFETs by irradiation with $$gamma$$-rays

Hishiki, Shigeomi; Reshanov, S. A.*; Oshima, Takeshi; Ito, Hisayoshi; Pensl, G.*

Materials Science Forum, 600-603, p.703 - 706, 2009/00

 Times Cited Count:1 Percentile:50.12

N-channel 6H-SiC MOSFETs has been investigated radiation effect. The MOSFETs were irradiated by $$gamma$$-rays up to 3.16 MGy(SiO$$_{2}$$) at room temperature. The electrical characteristic was estimated by Hall effect measurement and current vs. voltage measurement. The $$gamma$$-rays irradiated MOSFETs were observed that channel mobility increased due to decrease interface traps.

Journal Articles

Electrical characteristics of 6H-SiC MOSFETs after high dose irradiation

Oshima, Takeshi; Hishiki, Shigeomi*; Iwamoto, Naoya; Reshanov, S. A.*; Pensl, G.*; Kojima, Kazutoshi*; Kawano, Katsuyasu*

Proceedings of the 26th Symposium on Materials Science and Engineering, Research Center of Ion Beam Technology Hosei University, p.31 - 34, 2007/12

no abstracts in English

Journal Articles

Energetically deep defect centers in vapor-phase grown zinc oxide

Frank, T.*; Pensl, G.*; Tana-Zaera, R.*; Z$'u$$~n$iga-P$'e$rez, J.*; Mart$'i$nez-Tom$'a$s, C.*; Mu$~n$oz-Sanjos$'e$, V.*; Oshima, Takeshi; Ito, Hisayoshi; Hofmann, D.*; Pfisterer, D.*; et al.

Applied Physics A, 88(1), p.141 - 145, 2007/07

 Times Cited Count:47 Percentile:84.23(Materials Science, Multidisciplinary)

Deep Level Transient Spectroscopy (DLTS) measurements were carried out to investigate defects in vapor-phase grown ZnO crystals. The generation of defect center labeled E4 subsequent to annealing in different ambients was monitored. By conducting electron irradiations with energies, where either both the Zn- and O-sublattice are damaged or according to only the Zn-lattice, a chemical assignment to the defect centers E4 and E3 could be accomplished. DLTS investigations of ZnO samples under illumination give an evidence that E4 is a negative-U center.

Journal Articles

Hall effect and admittance measurements of n-channel 6H-SiC MOSFETs

Lee, K. K.*; Laube, M.*; Oshima, Takeshi; Ito, Hisayoshi; Pensl, G.*

Materials Science Forum, 556-557, p.791 - 794, 2007/00

no abstracts in English

Journal Articles

(Nitrogen/vacancy)-complex formation in SiC; Experiment and theory

Pensl, G.*; Schmid, F.*; Reshanov, S.*; Weber, H. B.*; Bockstedte, M.*; Mattausch, A.*; Pankratov, O.*; Oshima, Takeshi; Ito, Hisayoshi

Materials Science Forum, 556-557, p.307 - 312, 2007/00

no abstracts in English

Journal Articles

Deactivation of nitrogen donors in silicon carbide

Schmid, F.*; Reshanov, S. A.*; Weber, H. B.*; Pensl, G.*; Bockstedte, M.*; Mattausch, A.*; Pankratov, O.*; Oshima, Takeshi; Ito, Hisayoshi

Physical Review B, 74(24), p.245212_1 - 245212_11, 2006/12

 Times Cited Count:11 Percentile:48.8(Materials Science, Multidisciplinary)

Hexagonal SiC is co-implanted with silicon Si$$^{+}$$, carbon C$$^{+}$$, or neon Ne$$^{+}$$ ions along with nitrogen N$$^{+}$$ ions. Also hexagonal SiC irradiated with electrons e$$^{-}$$ of 200 keV energy. During the subsequent annealing step at temperatures above 1450 $$^{circ}$$C a deactivation of N donors and a reduction of the compensation are observed in the case of the Si$$^{+}$$/N$$^{+}$$ co-implantation and e$$^{-}$$ irradiation. Using Hall measurement, the N donor deactivation is studied as a function of the concentration of the co-implanted species and the annealing temperature. The formation of energetically deep defects is analyzed with deep level transient spectroscopy. A detailed theoretical analysis based on the density functional theory is conducted; it takes into account the kinetic mechanisms for the formation of N interstitial clusters and N-vacancy complexes. In accordance with all the experimental results, this analysis distinctly indicates that the (N$$ _{C}$$)$$_ {4}$$-V$$_{Si}$$ complex, which is thermally stable at high temperatures, is responsible for the N donor deactivation.

Journal Articles

Anomalous increase in effective channel mobility on $$gamma$$-irradiated p-channel SiC metal-oxide-semiconductor field-effect transistors containing step bunching

Lee, K. K.*; Oshima, Takeshi; Oi, Akihiko*; Ito, Hisayoshi; Pensl, G.*

Japanese Journal of Applied Physics, Part 1, 45(9A), p.6830 - 6836, 2006/09

 Times Cited Count:15 Percentile:51.29(Physics, Applied)

no abstracts in English

Journal Articles

Defect-engineering in SiC by ion implantation and electron irradiation

Pensl, G.*; Ciobanu, F.*; Frank, T.*; Kirmse, D.*; Krieger, M.*; Reshanov, S.*; Schmid, F.*; Weidner, M.*; Oshima, Takeshi; Ito, Hisayoshi; et al.

Microelectronic Engineering, 83(1), p.146 - 149, 2006/01

 Times Cited Count:14 Percentile:59.24(Engineering, Electrical & Electronic)

no abstracts in English

Journal Articles

Comparison of the electrical channel properties between dry- and wet-oxidized 6H-SiC MOSFETs investigated by Hall effect

Laube, M.*; Pensl, G.*; Lee, K. K.; Oshima, Takeshi

Materials Science Forum, 457-460, p.1381 - 1384, 2004/10

The electrical properties of n-channel 6H-SiC MOSFETs have been studied by temperature-dependent current-voltage and Hall effect measurements. The MOS transistors are either wet (sample A) or dry oxidized followed by a post-annealing step at 1100$$^{circ}$$C and a pyrogenic reoxidation at 800$$^{circ}$$C (sample B). Higher drain transconductance and saturation currents are observed in sample B. The Hall effect investigations show that this improvement in the performance of the MOS transistors (sample B) is caused by a lower degree of trapping of free electrons. The density of interface traps D$$_{IT}$$ close to the conduction band edge has been determined from the shift of the threshold voltage V$$_{TH}$$ as a function of the temperature and from the Hall effect results. D$$_{IT}$$ is about two times lower in sample B. The room temperature value of the electron Hall mobility is determined to be about 60 cm$$^{2}$$/Vs for both samples; it increases with decreasing temperature.

Journal Articles

Negative-U-centers in 4H- and 6H-SiC detected by spectral light excitation

Weidner, M.*; Pensl, G.*; Nagasawa, Hiroyuki*; Sch$"o$ner, A.*; Oshima, Takeshi

Materials Science Forum, 457-460, p.485 - 488, 2004/10

no abstracts in English

Journal Articles

Vacancy defects detected by positron annihilation

Kawasuso, Atsuo; Weidener, M.*; Redmann, F.*; Frank, T.*; Sperr, P.*; K$"o$gel, G.*; Yoshikawa, Masahito; Ito, Hisayoshi; Krause-Rehberg, R.*; Triftsh$"a$user, W.*; et al.

Silicon Carbide, p.563 - 584, 2004/00

no abstracts in English

Journal Articles

Polytype-dependent vacancy annealing studied by positron annihilation

Kawasuso, Atsuo; Yoshikawa, Masahito; Maekawa, Masaki; Ito, Hisayoshi; Chiba, Toshinobu*; Redmann, F.*; Rehberg, R. K.*; Weidner, M.*; Frank, T.*; Pensl, G.*

Materials Science Forum, 433-436, p.477 - 480, 2003/08

no abstracts in English

Journal Articles

Radiation-induced defects in 4H- and 6H-SiC epilayers studies by positron annihilation and deep-level transient spectroscopy

Kawasuso, Atsuo; Weidner, M.*; Redmann, F.*; Frank, T.*; Krause-Rehberg, R.*; Pensl, G.*; Sperr, P.*; Triftsh$"a$user, W.*; Ito, Hisayoshi

Materials Science Forum, 389-393, p.489 - 492, 2002/05

no abstracts in English

Journal Articles

Annealing behavior of vacancies and Z$$_{1/2}$$ levels in electron-irradiated 4H-SiC studied by positron annihilation and deep-level transient spectroscopy

Kawasuso, Atsuo; Redmann, F.*; Krause-Rehberg, R.*; Weidner, M.*; Frank, T.*; Pensl, G.*; Sperr, P.*; Triftsh$"a$user, W.*; Ito, Hisayoshi

Applied Physics Letters, 79(24), p.3950 - 3952, 2001/12

 Times Cited Count:38 Percentile:80.13(Physics, Applied)

no abstracts in English

29 (Records 1-20 displayed on this page)