Open AccessRadiative recombination and ultralong exciton photoluminescence lifetime in GaN freestanding film via two-photon excitation
Author(s) -
Yongchun Zhong,
Kam Sing Wong,
Weili Zhang,
D. C. Look
Publication year - 2006
Publication title -
applied physics letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 442
eISSN - 1077-3118
pISSN - 0003-6951
DOI - 10.1063/1.2219399
Subject(s) - photoluminescence , exciton , excited state , excitation , relaxation (psychology) , spontaneous emission , materials science , atomic physics , radiative transfer , recombination , photon , photoexcitation , wavelength , carrier lifetime , molecular physics , optoelectronics , physics , condensed matter physics , optics , laser , chemistry , silicon , quantum mechanics , psychology , social psychology , biochemistry , gene
We have measured the photoluminescence (PL) lifetime of a freestanding GaN film using one-photon and two-photon excitations to demonstrate the dramatic difference in exciton recombination dynamics at the surface and in the bulk. An ultralong exciton PL lifetime of 17.2 ns at 295 K is observed from a GaN freestanding film using two-photon excitation, whereas less than 100 ps lifetime is observed for one-photon excitation, suggesting that nonradiative processes from surface defects account for the short PL lifetime measured. A monotonic increase in two-photon excited PL lifetime with increasing temperature and the linear dependence of the exciton lifetime with emission wavelength show good agreement with the theoretical predictions, indicating that radiative recombination dominates for bulk excited state relaxation processes. (c) 2006 American Institute of Physics
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