TY  - SER
AU  - Gällström,Andreas
AU  - Leone,Stefano
AU  - Kordina,Olof
AU  - Son,Nguyen T.
AU  - Ivády,Viktor
AU  - Gali,Adam
AU  - Abrikosov,Igor A.
AU  - Janzén,Erik
AU  - Ivanov,Ivan G.
AU  - Magnusson,Björn
TI  - Optical properties and Zeeman spectroscopy of niobium in silicon carbide
KW  - зеемановское расщепление
KW  - экситонная люминесценция
KW  - гексагональные политипы
KW  - статьи в журналах
N1  - Библиогр.: 32 назв
N2  - The optical signature of niobium in the low-temperature photoluminescence spectra of three common polytypes of SiC (4H, 6H, and 15R) is observed and confirms the previously suggested concept that Nb occupies preferably the Si-C divacancy with both Si and C at hexagonal sites. Using this concept we propose a model considering a Nb-bound exciton, the recombination of which is responsible for the observed luminescence. The exciton energy is estimated using first-principles calculation and the result is in very good agreement with the experimentally observed photon energy in 4H SiC at low temperature. The appearance of six Nb-related lines in the spectra of the hexagonal 4H and 6H polytypes at higher temperatures is tentatively explained on the grounds of the proposed model and the concept that the Nb center can exist in both  C1h and C3v symmetries. The Zeeman splitting of the photoluminescence lines is also recorded in two different experimental geometries and the results are compared with theory based on phenomenological Hamiltonians. Our results show that Nb occupying the divacancy at the hexagonal site in the studied SiC polytypes behaves like a deep acceptor
UR  - http://vital.lib.tsu.ru/vital/access/manager/Repository/vtls:000625562
ER  -