Transformation and clustering of defects induced by electron irradiation in barium hollandite ceramics for radioactive cesium storage: Electron paramagnetic resonance study

2012 ◽  
Vol 111 (8) ◽  
pp. 083504 ◽  
Author(s):  
V. Aubin-Chevaldonnet ◽  
D. Gourier ◽  
D. Caurant ◽  
J.-M. Costantini
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Electron Irradiation ◽  
Electron Paramagnetic Resonance Study ◽  
Radioactive Cesium ◽  
Paramagnetic Resonance ◽  
Electron Paramagnetic

Electron Paramagnetic Resonance Study of Carbon Antisite-Vacancy Pair in p-Type 4H-SiC

2007 ◽  
Vol 556-557 ◽  
pp. 453-456 ◽  
Author(s):  
T. Umeda ◽  
Norio Morishita ◽  
Takeshi Ohshima ◽  
Hisayoshi Itoh ◽  
Junichi Isoya
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Electron Irradiation ◽  
Electron Paramagnetic Resonance Study ◽  
Dangling Bond ◽  
Charged State ◽  
Paramagnetic Resonance ◽  
Vacancy Pair ◽  
P Type ◽  
Electron Paramagnetic ◽  
Positively Charged

Carbon antisite-vacancy pair (CSiVC) is a fundamental defect in SiC, and is theoretically predicted to be very stable in p-type materials. However, this pair was found only in the form of a negatively charged state (i.e., the SI5 center = CSiVC −) in n-type and semi-insulating 4H-SiC, and yet, its presence has not been shown in p-type SiC. In this report, we present the first EPR observation on positively charged CSiVC pairs in p-type 4H-SiC. By carefully examining p-type samples after electron irradiation, we found a pair of new defects with C3v and C1h symmetries. They correspond to “c-axial” pairs (C3v) and “basal” pairs (C1h) of CSiVC +, respectively. The positively charged pairs are characterized by a strong 13C hyperfine interaction due to a dangling bond on a carbon antisite (CSi), which is successfully resolved for the c-axial pairs.

Electron Paramagnetic Resonance Study of the HEI4/SI5 Center in 4H-SiC

2006 ◽  
Vol 527-529 ◽  
pp. 543-546 ◽  
Author(s):  
T. Umeda ◽  
Nguyen Tien Son ◽  
Junichi Isoya ◽  
Norio Morishita ◽  
Takeshi Ohshima ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Charge State ◽  
Electron Irradiation ◽  
High Intensity ◽  
Negative Charge ◽  
Electron Paramagnetic Resonance Study ◽  
Paramagnetic Resonance ◽  
Vacancy Pair ◽  
Electron Paramagnetic ◽  
Hyperfine Structures

We present new electron-paramagnetic-resonance (EPR) data on the HEI4/SI5 center in 4H-SiC. So far, the SI5 (SI-5) center has been observed only in as-grown SiC substrates; however, we found that it can be created by electron irradiation to commercial n-type 4H-SiC. The artificially created SI5 center, which we had preliminary called HEI4, was found to be identical with the SI5 center in as-grown SiC. A high-intensity HEI4/SI5 spectrum of irradiated SiC revealed clear hyperfine structures of 29Si and 13C, which enabled us to identify the origin of this center as a carbon antisite-vacancy pair in the negative charge state (CSi-VC –). We assessed its electronic levels using photo-EPR.

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