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Electronic structure of the nitrogen donors in 6H SiC as studied by pulsed ENDOR and TRIPLE ENDOR spectroscopy

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  • Dedicated to Prof. Reinhard Kirmse on the occasion of his 65th birthday

Abstract

The nitrogen (N) donors in 6H SiC were investigated by field sweep electron spin echo (FS ESE), pulsed electron nuclear double resonance (ENDOR) and pulsed General TRIPLE ENDOR spectroscopy. The 29Si and 13C superhyperfine (shf) lines observed in the FS ESE and ENDOR spectra of N in n-type 6H SiC were assigned by pulsed General TRIPLE resonance spectroscopy to the specific carbon (C) and silicon (Si) atoms located in the environment of N donors residing at two quasi-cubic lattice sites (Nk1, Nk2) in 6H SiC. As a result, the largest value of the shf interaction was found with Si atoms for the N donors at the hexagonal (Nh) and quasi-cubic site Nk1, while for Nk2 the largest value of the shf interaction was found with C atoms. It gives us the argument to consider that N substitute different lattice sites in 6H SiC lattice. The relative signs of the shf interaction (shfi) constants for Nk1 and Nk2 with 29Si and 13C nuclei located in the nearest-neighbor, next nearest-neighbor, and outer shells are found from the TRIPLE ENDOR spectra to be positive for C atoms and negative for Si atoms. From the comparison of the experimentally obtained shfi constants with the theory, the electronic spin-density distribution over the 29Si and 13C nuclei located in the nearest neighbor shells of N donors has been obtained taking into account the Kohn–Luttinger interference effect. The position of the conduction band minimum along the ML-line was determined to be at k0z/kmax = 0.2 ± 0.05.

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