Probing exciton-phonon interaction in AlN epilayers by photoluminescence

Sedhain, A.; Li, J.; Lin, J. Y.; Jiang, Hongxing

doi:10.1063/1.3206672

Cited by 25 publications

(12 citation statements)

References 27 publications

(20 reference statements)

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“…At 10 K, the band edge emission peak is at 6.06 eV. Detailed optical properties of AlN epilayers grown on sapphire substrates are also reported elsewhere 2, 5, 18–20.…”

Section: Resultsmentioning

confidence: 88%

Three‐step growth method for high quality AlN epilayers

Nakarmi

Cai

Lin

et al. 2011

Physica Status Solidi (a)

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We report a three-step growth method to grow thick and high quality aluminum nitride (AlN) epilayers on sapphire substrates by metal organic chemical vapor deposition (MOCVD). The three-step growth method begins with a deposition of a thin AlN buffer layer at 950 8C followed by an intermediate AlN (I-AlN) layer at 1100 8C, and finally a thick AlN epilayer at high temperature around 1325 8C. AlN epilayers grown by this method have smooth surfaces, narrow width of X-ray rocking curves, and strong band edge photoluminescence (PL) emissions with low impurity emissions. Transmission electron microscopy revealed that most of the threading dislocations are annihilated within 300 nm. Stacking faults are greatly reduced in epilayers grown by this method resulting in very low screw type threading dislocation density. Dominant threading dislocations in the AlN epilayers are edge type originated from misfit dislocations (MD).

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“…At 10 K, the band edge emission peak is at 6.06 eV. Detailed optical properties of AlN epilayers grown on sapphire substrates are also reported elsewhere 2, 5, 18–20.…”

Section: Resultsmentioning

confidence: 88%

Three‐step growth method for high quality AlN epilayers

Nakarmi

Cai

Lin

et al. 2011

Physica Status Solidi (a)

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“…32 In this study, a larger S-factor, i.e., a stronger phonon-exciton coupling in nanowires, could also originate from the significantly improved material quality, since the emission intensity of phonon replicas can be significantly reduced by the scattering of impurities and defects. 31 Additionally, it is worth highlighting that the frequency of the SO-phonon in nanowires can be tuned by changing the morphology, wire density, and the dielectric constant of the FIG. 4.…”

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confidence: 99%

“…12,29,30 The coupling strength between phonon and exciton can be evaluated by using the Huang-Rhys (H-R) factor, i.e., S-factor, based on the equation I n ¼ I 0 (S n /n!). 31 Here, n ¼ 0, 1, 2, 3,…, represent the number of LO-phonons involved, I n is the emission intensity of the n th phonon replica and I 0 is the intensity of the main emission line. Accordingly, based on Figs.…”

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confidence: 99%

Optical properties of strain-free AlN nanowires grown by molecular beam epitaxy on Si substrates

Wang

Zhao

Connie

et al. 2014

Applied Physics Letters

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The optical properties of catalyst-free AlN nanowires grown on Si substrates by molecular beam epitaxy were investigated. Such nanowires are nearly free of strain, with strong free exciton emission measured at room temperature. The photoluminescence intensity is significantly enhanced, compared to previously reported AlN epilayer. Moreover, the presence of phonon replicas with an energy separation of ∼100 meV was identified to be associated with the surface-optical phonon rather than the commonly reported longitudinal-optical phonon, which is further supported by the micro-Raman scattering experiments.

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“…From this relation, the optical-phonon energy of the local vibration of the Gd-N bond is estimated to be approximately 65 meV, which is moderately close to the measured energy difference. Excitons created in AlN are inelastically scattered in k space, where the exciton-phonon interaction in AlN is strong 32 because of the small dielectric constant of AlN and the resultant strong Coulomb interaction. Thus, efficient energy transfer into Gd 3þ centers can take place.…”

Section: Thermal Annealing Effects On Atomically Sharp Uv Luminementioning

confidence: 99%

Thermal annealing effects on ultra-violet luminescence properties of Gd doped AlN

Ishizu

Tsuji

Harada

et al. 2015

Journal of Applied Physics

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We studied energy transfer from AlN to doped Gd 3þ ions as a function of the post-thermal annealing temperature. Gd-doped AlN thin films were deposited on fused-silica substrates using a reactive radio-frequency magnetron sputtering technique. The film is a c-axis oriented polycrystal. The intraorbital electron transition in Gd 3þ showed an atomically sharp luminescence at 3.9 eV (318 nm). The photoluminescence (PL) excitation spectrum exhibited a resonant peak, indicating efficient energy transfer from the host AlN crystal to Gd 3þ ions. The PL intensity increases approximately ten times by thermal annealing. The PL decay lifetime becomes long with annealing, and mid-gap luminescence relating to the crystal defects in AlN was also found to be reduced by annealing. These results suggest that energy dissipation of excited carriers in AlN was suppressed by annealing, and the efficiency of energy transfer into Gd 3þ was improved. V C 2015 AIP Publishing LLC.

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Probing exciton-phonon interaction in AlN epilayers by photoluminescence

Cited by 25 publications

References 27 publications

Three‐step growth method for high quality AlN epilayers

Three‐step growth method for high quality AlN epilayers

Optical properties of strain-free AlN nanowires grown by molecular beam epitaxy on Si substrates

Thermal annealing effects on ultra-violet luminescence properties of Gd doped AlN

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