Open AccessTrap and nonradiative centers in Ba_3Si_6O_12N_2:Eu^2+ phosphors observed by thermoluminescence and two-wavelength excited photoluminescence methods
Author(s) -
TingTing Li,
Norihiko Kamata,
Yosuke Kotsuka,
Tsuguo Fukuda,
Zentaro Honda,
Tomoyuki Kurushima
Publication year - 2015
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.23.016511
Subject(s) - phosphor , photoexcitation , excited state , photoluminescence , thermoluminescence , materials science , wavelength , excitation , atomic physics , luminescence , optoelectronics , optics , physics , quantum mechanics
We have studied trap centers and nonradiative (NRR) recombination centers in a Ba3Si6O12N2:Eu2+ (BSON), one of promising materials for efficient and stable phosphors in white LED lamp applications. The energy distribution of four trap centers was obtained by thermo-luminescence (TL) with the excitation energy of 5.59eV. By superposing a below-gap excitation light of 1.77eV and observing the intensity change of the 5d-4f emission of Eu2+ centered at 2.36eV in our two-wavelength excited photoluminescence (TWEPL) measurement, both transient and steady state enhancement were observed. Such peculiar behavior of photo-stimulation is attributed to the coexistence of trap centers and NRR centers: the photoexcitation of electrons from trap centers generates the transient component, while that from NRR centers maintains the steady state component. An optical detection of relatively faint contribution of defects became possible in order to improve further the reliability and efficiency of phosphor materials.