A full vibronic spectrum has been measured for the first time by LNT Cathodoluminescence in HPHT c-BN amber-coloured microcrystalline samples. The related BN1 centre at 3.293 eV seems not created by electron irradiation in this case and the accurately determined phonon energy (141±3 meV) could be related to LO phonon at X point in Brillouin Zone (BZ) of c-BN, as determined by CL results obtained at indirect gap. Consequently, BN1 centre has not the full cubic symmetry of c-BN, as being due to N interstitials. The interpretation of the results is possibly twofold: either we are observing a vibronic spectrum with ZPL at BN1 centre, together with other two centres called PF-1 and PF-2 at 3.573 and at 3.412 eV, respectively, or, since all the 6 or 7 observed peaks are exactly equally spaced, the whole vibronic spectrum is related to a ZPL line at 3.573 eV. This new interpretation seems to be in better agreement with the general theory of colour centres.

Low temperature CL investigation of BN1 vibronic structure in c-BN

COSSIO, Roberto;VITTONE, Ettore;LO GIUDICE, Alessandro;MANFREDOTTI, Claudio;
2006-01-01

Abstract

A full vibronic spectrum has been measured for the first time by LNT Cathodoluminescence in HPHT c-BN amber-coloured microcrystalline samples. The related BN1 centre at 3.293 eV seems not created by electron irradiation in this case and the accurately determined phonon energy (141±3 meV) could be related to LO phonon at X point in Brillouin Zone (BZ) of c-BN, as determined by CL results obtained at indirect gap. Consequently, BN1 centre has not the full cubic symmetry of c-BN, as being due to N interstitials. The interpretation of the results is possibly twofold: either we are observing a vibronic spectrum with ZPL at BN1 centre, together with other two centres called PF-1 and PF-2 at 3.573 and at 3.412 eV, respectively, or, since all the 6 or 7 observed peaks are exactly equally spaced, the whole vibronic spectrum is related to a ZPL line at 3.573 eV. This new interpretation seems to be in better agreement with the general theory of colour centres.
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c-BN; Cathodoluminescence; Vibronic structure; Defect centres
R. COSSIO; F. FIZZOTTI; E. VITTONE; A. LO GIUDICE; C. MANFREDOTTI; S. NISTOR
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/39139
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