Near band gap photoluminescence properties of hexagonal boron nitride

Luc Museur (1) , Andreï Kanaev (2)

1 LPL - Laboratoire de Physique des Lasers
2 LIMHP - Laboratoire d'Ingénierie des Matériaux et des Hautes Pressions

Near band-gap luminescence (h>5 eV) of hexagonal boron nitride has been studied by means of the time- and energy-resolved photoluminescence spectroscopy method. Two emissions have been observed at 5.5 eV and 5.3 eV. The high-energy emission at 5.5 eV is composed of fixed sub-bands assigned to bound excitons at 5.47 eV, 5.56 eV and 5.61 eV. The non-structured low-energy emission at 5.3 eV undergoes a large blue shift (up to 120 meV) with a linear slope <1 with increasing excitation energy Eexc. At Eexc> 5.7 eV, the band position is fixed and marks the transition from the Raman to the photoluminescence regime. We assign the 5.3 eV band to quasi donor-acceptor pair (q-DAP) states due to electrostatic band fluctuations induced by charged defects. The shift is explained by photo-induced neutralization of charged defect states. The absence of contribution to the q-DAP luminescence from exciton suggests the existence of a large exciton binding energy, which is qualitatively consistent with theoretical predictions.

Mots clés: Boron nitride; photoluminescence; excitons; DAP

Domaines: Optique / photonique; Optique [physics.optics]; Science des matériaux [cond-mat.mtrl-sci]; Matériaux

Luc Museur, Andreï Kanaev. Near band gap photoluminescence properties of hexagonal boron nitride. Journal of Applied Physics, 2008, pp.1. ⟨hal-00269248⟩