Найдено научных статей и публикаций: 4, для научной тематики: ESE
1.
D.V. Savchenko, E.N. Kalabukhova, , S.N. Lukin, E.N. Mokhov, J. Hoentsch, A. Pöppl
- Physica B , 2009
D-band EPR, X-band FS ESE and pulsed ENDOR studies of the additional nitrogen (N) related centers
observed in highly compensated n-type 6H-SiC wafers are presented. The D-band EPR and X-band FS
ESE spectrum consists of the 14N hyperfine (hf) triplet lines of the N donors incorporated at the two
q...
D-band EPR, X-band FS ESE and pulsed ENDOR studies of the additional nitrogen (N) related centers
observed in highly compensated n-type 6H-SiC wafers are presented. The D-band EPR and X-band FS
ESE spectrum consists of the 14N hyperfine (hf) triplet lines of the N donors incorporated at the two
quasi-cubic (Nc1, Nc2) sites with the intensity ratio of INc1/INc2 ¼ 0.7 and three additional triplet lines.
X-band pulsed ENDOR spectra have shown intense 14N ENDOR signals of Nc1, Nc2 centers and new 14N
lines due to the N related centers N1, N2, N3 with the isotropic hf splitting: 21.04, 26.43, 29.77MHz,
respectively. It was found that the g-tensors of the N2 and N3 triplet lines coincide with those of N on
quasi-cubic Nc2 site. The g-tensor of the third N1 triplet lines corresponds to the average value of the Nc1
and Nc2 spectrum: gðN1Þ 1
2½gðNc1Þ þ gðNc2Þ. It was suggested that N1 center with Aiso ¼ 21.04MHz is
due to the spin coupling between N on two quasi-cubic Nc1 and Nc2 sites while two others are
tentatively attributed to the N pairs formed between N atoms on one quasi-cubic Nc2 site.
2.
D.V. Savchenko, A. Pöppl, E.N. Kalabukhova, E.F. Venger, M.P. Gadzira, G.G. Gnesin
- Semiconductor Physics, Quantum Electronics & Optoelectronics , 2010
Nonstoichiometric b-SiC nanoparticles (np-SiC) have been studied by electron
paramagnetic resonance (EPR) and pulsed magnetic resonance methods including field
swept electron spin echo (FS ESE), pulsed electron nuclear double resonance (ENDOR)
and hyperfine sublevel correlation spectroscopy (HYSC...
Nonstoichiometric b-SiC nanoparticles (np-SiC) have been studied by electron
paramagnetic resonance (EPR) and pulsed magnetic resonance methods including field
swept electron spin echo (FS ESE), pulsed electron nuclear double resonance (ENDOR)
and hyperfine sublevel correlation spectroscopy (HYSCORE). Four ESE signals related
to the paramagnetic centers labeled D1, D2, D3, D4 with g = 2.0043, g = 2.0029,
g = 2.0031, g = 2.0037 were resolved in FS ESE spectrum due to their different spin
relaxation times. As deduced from the study of the superhyperfine structure of the D2
defect by FS ESE, pulse ENDOR and HYSCORE methods the dominant paramagnetic
center is a carbon vacancy (VC) localized in b-SiC crystalline phase of the np-SiC. The
parameters of the D2 center coincide with those found for the VC in np-SiC obtained by
laser pyrolysis method. Three other defects were identified by comparison of their EPR
parameters with the microstructure of the np-SiC. The D1 defect was attributed to the VC
vacancy located in b-SiC crystalline phase. The D3 defect is identified with the carbon
dangling bonds located in the carbon excess phase. The D4 defect was assigned to a
threefold-coordinated Si atom bonded with one nitrogen atom, resulting in the formation
of the local bonding Si-Si2N configuration in a-Si3N4 phase.
3.
D.V. Savchenko, A. Pöppl, E.N. Kalabukhova, S. Greulich-Weber, E. Rauls, W.G. Schmidt, U. Gerstmann
- Mat. Sci. Forum , 2009
EPR and ESE in nitrogen doped 4H- and 6H-SiC show besides the well known triplet
lines of 14N on quasi-cubic (Nc,k) and hexagonal (Nc,h) sites additional lines (Nx) of comparatively
low intensity providing half the hf splitting of Nc,k. Frequently re-interpreted as spin-forbidden
lines, arising f...
EPR and ESE in nitrogen doped 4H- and 6H-SiC show besides the well known triplet
lines of 14N on quasi-cubic (Nc,k) and hexagonal (Nc,h) sites additional lines (Nx) of comparatively
low intensity providing half the hf splitting of Nc,k. Frequently re-interpreted as spin-forbidden
lines, arising from Nc,k pairs and triads or resulting from hopping conductivity, only recently the
theoretical calculation of the corresponding g-tensors lead to a tentative model of distant NC donor
pairs on inequivalent lattice sites which are coupled to S = 1 assuming a fine-structure splitting too
small to be observed in the EPR and ESE experiments. In this work, we present ESE nutation
measurements confirming S = 1 for the Nx center. Analysing the nutation frequencies in
comparison with that of the Nc,k (S = 1/2) spectrum as well as the line width of ESE and EPR
spectra we obtain a rough estimate between 5×104 cm-1 and 50×104 cm-1 for the fine-structure
splitting demonstrating efficient spin-coupling between nitrogen donors in 4H-SiC.
4.
D.V. Savchenko, E.N. Kalabukhova, V.S. Kiselev, J. Hoentsch, A. Pöppl
- Phys. Status Solidi B , 2009
The X-, Q-band field-sweep electron spin echo (FS ESE) study of n-type 6H SiC wafers shows besides the well known hyperfine (hf) triplet lines of 14N on two quasi-cubic (Nc1, Nc2) and hex-agonal (Nh) sites additional triplet lines (Nx) of comparatively low intensity with a g-tensor of about the aver...
The X-, Q-band field-sweep electron spin echo (FS ESE) study of n-type 6H SiC wafers shows besides the well known hyperfine (hf) triplet lines of 14N on two quasi-cubic (Nc1, Nc2) and hex-agonal (Nh) sites additional triplet lines (Nx) of comparatively low intensity with a g-tensor of about the average value of the Nc2 and Nh spectrum at 4.2 K. The Nx triplet has half of the hf splitting with respect to the nitrogen residing at cubic sites Nc2. Pulsed electron nuclear double resonance (ENDOR) measure-ments performed on the Nx EPR triplet line demonstrate that there is an efficient spin-coupling between Nh and Nx nitrogen re-lated centers. The Nx triplet lines were attributed to distant donor Nc–Nh pairs between nitrogen atoms residing at quasi-cubic and hexagonal sites having a total electron spin S = 1, which were found before in n-type 4H SiC. Based on Q-band FS ESE and X-band pulsed ENDOR measurements the values of the hf interac-tion for Nc1, Nc2 were reassigned with respect to the assignment accepted hitherto.
The super hyperfine (shf) interaction with neighboring atoms of nitrogen on the quasi-cubic lattice sites was studied by FS ESE and pulsed ENDOR. The new shf lines due to 29Si and 13C atoms with large shf interaction which were not observed previously were found in nitrogen FS ESE and ENDOR spectra. One of them, with the largest shf splitting (23.12 MHz), were attributed to the 29Si atoms along the c-axis in nearest-neighbor positions of nitrogen on the quasi-cubic sites which unambiguously confirms that nitrogen substitute carbon lattice site in 6H SiC.