Hai-yun Wang, Hui-min Weng, Xian-yi Zhou. Defect Characterization of 6H-SiC Studied by Slow Positron Beam[J]. Chinese Journal of Chemical Physics , 2008, 21(4): 333-338. doi: 10.1088/1674-0068/21/04/333-338
Citation: Hai-yun Wang, Hui-min Weng, Xian-yi Zhou. Defect Characterization of 6H-SiC Studied by Slow Positron Beam[J]. Chinese Journal of Chemical Physics , 2008, 21(4): 333-338. doi: 10.1088/1674-0068/21/04/333-338

Defect Characterization of 6H-SiC Studied by Slow Positron Beam

doi: 10.1088/1674-0068/21/04/333-338
Funds:  This work was supported by the National Natural Science Foundation of China (No.10175061) and the Nanjing University of Posts and Telecommunications Foundation of China (No.NY207010)
  • Received Date: 2008-03-16
  • Rev Recd Date: 2008-04-19
  • The defect formation and annealing behavior in as-grown and electron-irradiated 6H-SiC wafers were investi-gated by variable-energy slow positron beam. For the n-type as-grown samples, it was found that annealing decreased the defect concentration due to recombination with interstitial, and when it was annealed at 1400 ±C for 30 min in vacuum, a 20 nm thick Si layer was found on the top of SiC substrate, which is a direct proof of the Si atom diffusing to the surface when annealed at the high temperature stages. During the high temperature annealing stage, we found an obvious surface effect occurred that induced the higher S parameter close to the surface. This may be caused by the diffusion of the Si atoms to the surface during annealing. After 10 MeV electron irradiation of the n-type 6H-SiC, the positron effective diffusion length decreased from 86.2 nm to 39.1 nm. This shows that there are some defects created in n-type 6H-SiC. But in the p-type 6H-SiC irradiated by 10 MeV electrons, the change is very small. This may be because of the opposite charge of the vacancy defects. The same annealing behavior as that of as-grown 6H-SiC samples was also observed for the 1.8 MeV electron-irradiated 6H-SiC samples except that after being annealed at 300 ±C, its defect concentration increased. This may be explained as the generation of carbon vacancies, due to either the recombination between divacancies and silicon interstitial, or the charge of the charge states.
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Defect Characterization of 6H-SiC Studied by Slow Positron Beam

doi: 10.1088/1674-0068/21/04/333-338
Funds:  This work was supported by the National Natural Science Foundation of China (No.10175061) and the Nanjing University of Posts and Telecommunications Foundation of China (No.NY207010)

Abstract: The defect formation and annealing behavior in as-grown and electron-irradiated 6H-SiC wafers were investi-gated by variable-energy slow positron beam. For the n-type as-grown samples, it was found that annealing decreased the defect concentration due to recombination with interstitial, and when it was annealed at 1400 ±C for 30 min in vacuum, a 20 nm thick Si layer was found on the top of SiC substrate, which is a direct proof of the Si atom diffusing to the surface when annealed at the high temperature stages. During the high temperature annealing stage, we found an obvious surface effect occurred that induced the higher S parameter close to the surface. This may be caused by the diffusion of the Si atoms to the surface during annealing. After 10 MeV electron irradiation of the n-type 6H-SiC, the positron effective diffusion length decreased from 86.2 nm to 39.1 nm. This shows that there are some defects created in n-type 6H-SiC. But in the p-type 6H-SiC irradiated by 10 MeV electrons, the change is very small. This may be because of the opposite charge of the vacancy defects. The same annealing behavior as that of as-grown 6H-SiC samples was also observed for the 1.8 MeV electron-irradiated 6H-SiC samples except that after being annealed at 300 ±C, its defect concentration increased. This may be explained as the generation of carbon vacancies, due to either the recombination between divacancies and silicon interstitial, or the charge of the charge states.

Hai-yun Wang, Hui-min Weng, Xian-yi Zhou. Defect Characterization of 6H-SiC Studied by Slow Positron Beam[J]. Chinese Journal of Chemical Physics , 2008, 21(4): 333-338. doi: 10.1088/1674-0068/21/04/333-338
Citation: Hai-yun Wang, Hui-min Weng, Xian-yi Zhou. Defect Characterization of 6H-SiC Studied by Slow Positron Beam[J]. Chinese Journal of Chemical Physics , 2008, 21(4): 333-338. doi: 10.1088/1674-0068/21/04/333-338

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