Luminescence and energy-transfer mechanisms in Eu 3 + -doped GaN epitaxial films
Luminescence and energy-transfer mechanisms in Eu 3 + -doped GaN epitaxial films
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DOI：
10.1103/physrevb.81.035207
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发表时间：
2010-01
影响因子：
3.7
通讯作者：
Shinya Higuchi;A. Ishizumi;J. Sawahata;K. Akimoto;Y. Kanemitsu
中科院分区：
文献类型：
--
作者：
Shinya Higuchi;A. Ishizumi;J. Sawahata;K. Akimoto;Y. Kanemitsu
We studied the photoluminescence (PL) and energy-transfer processes in ${\text{Eu}}^{3+}$-doped GaN epitaxial films by means of microscopic PL imaging spectroscopy. ${\text{Eu}}^{3+}$-doped GaN epitaxial films exhibited blue luminescence due to bound-exciton recombinations in GaN host crystals and red luminescence due to intra-$4f$ transitions of ${\text{Eu}}^{3+}$ ions. We found an anticorrelation between the exciton and ${\text{Eu}}^{3+}$ PL intensities in space-resolved PL images, indicating that energy transfer from GaN crystals to ${\text{Eu}}^{3+}$ ions determines the ${\text{Eu}}^{3+}$ luminescence intensity. PL and PL excitation spectra showed that efficient ${\text{Eu}}^{3+}$ luminescence is caused by two different excitation processes: energy transfer from the low-energy charge-transfer (CT) states to ${\text{Eu}}^{3+}$ ions or from the delocalized states above the band edge of GaN crystals to ${\text{Eu}}^{3+}$ ions. The energy-transfer process from the CT state to ${\text{Eu}}^{3+}$ ions dominates the ${\text{Eu}}^{3+}$ luminescence.
We studied the photoluminescence (PL) and energy-transfer processes in ${\text{Eu}}^{3+}$-doped GaN epitaxial films by means of microscopic PL imaging spectroscopy. ${\text{Eu}}^{3+}$-doped GaN epitaxial films exhibited blue luminescence due to bound-exciton recombinations in GaN host crystals and red luminescence due to intra-$4f$ transitions of ${\text{Eu}}^{3+}$ ions. We found an anticorrelation between the exciton and ${\text{Eu}}^{3+}$ PL intensities in space-resolved PL images, indicating that energy transfer from GaN crystals to ${\text{Eu}}^{3+}$ ions determines the ${\text{Eu}}^{3+}$ luminescence intensity. PL and PL excitation spectra showed that efficient ${\text{Eu}}^{3+}$ luminescence is caused by two different excitation processes: energy transfer from the low-energy charge-transfer (CT) states to ${\text{Eu}}^{3+}$ ions or from the delocalized states above the band edge of GaN crystals to ${\text{Eu}}^{3+}$ ions. The energy-transfer process from the CT state to ${\text{Eu}}^{3+}$ ions dominates the ${\text{Eu}}^{3+}$ luminescence.