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Luminescence studies on green emitting InGaN/GaN MQWs implanted with nitrogen.

Sousa MA, Esteves TC, Sedrine NB, Rodrigues J, Lourenço MB, Redondo-Cubero A, Alves E, O'Donnell KP, Bockowski M, Wetzel C, Correia MR, Lorenz K, Monteiro T - Sci Rep (2015)

Bottom Line: The as-grown and as-implanted samples were found to exhibit a single green emission band attributed to localized excitons in the QW, although the N implantation leads to a strong reduction of the PL intensity.The green band was found to be surprisingly stable on annealing up to 1400°C.This band is more intense for the implanted sample, suggesting that defects generated by N implantation, likely related to the diffusion/segregation of indium (In), have been optically activated by the thermal treatment.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Física e I3N, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.

ABSTRACT
We studied the optical properties of metalorganic chemical vapour deposited (MOCVD) InGaN/GaN multiple quantum wells (MQW) subjected to nitrogen (N) implantation and post-growth annealing treatments. The optical characterization was carried out by means of temperature and excitation density-dependent steady state photoluminescence (PL) spectroscopy, supplemented by room temperature PL excitation (PLE) and PL lifetime (PLL) measurements. The as-grown and as-implanted samples were found to exhibit a single green emission band attributed to localized excitons in the QW, although the N implantation leads to a strong reduction of the PL intensity. The green band was found to be surprisingly stable on annealing up to 1400°C. A broad blue band dominates the low temperature PL after thermal annealing in both samples. This band is more intense for the implanted sample, suggesting that defects generated by N implantation, likely related to the diffusion/segregation of indium (In), have been optically activated by the thermal treatment.

No MeSH data available.


Related in: MedlinePlus

RT normalized PL (obtained under 3.8 eV and 3.1 eV excitations) and PLE spectra (monitored at 2.1 eV; 590 nm) to the unit peak height of the #as-grown sample.Inset: photograph of the low temperature emission. Energy dependent PL decay measurements obtained with 3.36 eV (λexc = 370 nm) nanoLED pulsed excitation.
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f1: RT normalized PL (obtained under 3.8 eV and 3.1 eV excitations) and PLE spectra (monitored at 2.1 eV; 590 nm) to the unit peak height of the #as-grown sample.Inset: photograph of the low temperature emission. Energy dependent PL decay measurements obtained with 3.36 eV (λexc = 370 nm) nanoLED pulsed excitation.

Mentions: Figure 1 (a) shows the RT PL and PLE spectra at RT and the visual appearance (in inset) of the as-grown InGaN/GaN MQW sample under He-Cd excitation at 14 K. The green band (GB) emission peak position, near 2.3 eV, was found to be slightly dependent on the measured spot, likely due to indium nitride compositional heterogeneities in the alloy and/or well width fluctuations789. The full width at half maximum of the GB PL at RT (~180 meV) is in agreement with those reported for similar structures6. The PLE spectrum indicates that GB emission may be achieved by pumping the samples both above and below the GaN bandgap; a wide excitation band with an onset at ~2.5 eV precedes a steep increase at the GaN absorption edge. Pumping the ternary alloy directly, with excitation below the GaN band edge reproduces the emission band nearly exactly, suggesting that the lower energy excitation band corresponds to local MQW–related absorption. The broadening of the excitation band quantifies the spatial composition fluctuations in the InGaN/GaN structure1011. The PL broad emission correlated with compositional and well width fluctuations identified by transmission electron microscopy in the MQW samples (to be published elsewhere) agrees well with the localized excitons model for the recombination processes.


Luminescence studies on green emitting InGaN/GaN MQWs implanted with nitrogen.

Sousa MA, Esteves TC, Sedrine NB, Rodrigues J, Lourenço MB, Redondo-Cubero A, Alves E, O'Donnell KP, Bockowski M, Wetzel C, Correia MR, Lorenz K, Monteiro T - Sci Rep (2015)

RT normalized PL (obtained under 3.8 eV and 3.1 eV excitations) and PLE spectra (monitored at 2.1 eV; 590 nm) to the unit peak height of the #as-grown sample.Inset: photograph of the low temperature emission. Energy dependent PL decay measurements obtained with 3.36 eV (λexc = 370 nm) nanoLED pulsed excitation.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4389667&req=5

f1: RT normalized PL (obtained under 3.8 eV and 3.1 eV excitations) and PLE spectra (monitored at 2.1 eV; 590 nm) to the unit peak height of the #as-grown sample.Inset: photograph of the low temperature emission. Energy dependent PL decay measurements obtained with 3.36 eV (λexc = 370 nm) nanoLED pulsed excitation.
Mentions: Figure 1 (a) shows the RT PL and PLE spectra at RT and the visual appearance (in inset) of the as-grown InGaN/GaN MQW sample under He-Cd excitation at 14 K. The green band (GB) emission peak position, near 2.3 eV, was found to be slightly dependent on the measured spot, likely due to indium nitride compositional heterogeneities in the alloy and/or well width fluctuations789. The full width at half maximum of the GB PL at RT (~180 meV) is in agreement with those reported for similar structures6. The PLE spectrum indicates that GB emission may be achieved by pumping the samples both above and below the GaN bandgap; a wide excitation band with an onset at ~2.5 eV precedes a steep increase at the GaN absorption edge. Pumping the ternary alloy directly, with excitation below the GaN band edge reproduces the emission band nearly exactly, suggesting that the lower energy excitation band corresponds to local MQW–related absorption. The broadening of the excitation band quantifies the spatial composition fluctuations in the InGaN/GaN structure1011. The PL broad emission correlated with compositional and well width fluctuations identified by transmission electron microscopy in the MQW samples (to be published elsewhere) agrees well with the localized excitons model for the recombination processes.

Bottom Line: The as-grown and as-implanted samples were found to exhibit a single green emission band attributed to localized excitons in the QW, although the N implantation leads to a strong reduction of the PL intensity.The green band was found to be surprisingly stable on annealing up to 1400°C.This band is more intense for the implanted sample, suggesting that defects generated by N implantation, likely related to the diffusion/segregation of indium (In), have been optically activated by the thermal treatment.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Física e I3N, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.

ABSTRACT
We studied the optical properties of metalorganic chemical vapour deposited (MOCVD) InGaN/GaN multiple quantum wells (MQW) subjected to nitrogen (N) implantation and post-growth annealing treatments. The optical characterization was carried out by means of temperature and excitation density-dependent steady state photoluminescence (PL) spectroscopy, supplemented by room temperature PL excitation (PLE) and PL lifetime (PLL) measurements. The as-grown and as-implanted samples were found to exhibit a single green emission band attributed to localized excitons in the QW, although the N implantation leads to a strong reduction of the PL intensity. The green band was found to be surprisingly stable on annealing up to 1400°C. A broad blue band dominates the low temperature PL after thermal annealing in both samples. This band is more intense for the implanted sample, suggesting that defects generated by N implantation, likely related to the diffusion/segregation of indium (In), have been optically activated by the thermal treatment.

No MeSH data available.


Related in: MedlinePlus