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Photoluminescence studies of a perceived white light emission from a monolithic InGaN/GaN quantum well structure.

Ben-Sedrine N, Esteves TC, Rodrigues J, Rino L, Correia MR, Sequeira MC, Neves AJ, Alves E, Bockowski M, Edwards PR, O'Donnell KP, Lorenz K, Monteiro T - Sci Rep (2015)

Bottom Line: As-grown and thermally annealed samples at high temperature (1000 °C, 1100 °C and 1200 °C) and high pressure (1.1 GPa) were analysed by spectroscopic techniques, and the annealing effect on the photoluminescence is deeply explored.Under laser excitation of 3.8 eV at room temperature, the as-grown structure exhibits two main emission bands: a yellow band peaked at 2.14 eV and a blue band peaked at 2.8 eV resulting in white light perception.The room temperature white emission is studied as a function of incident power density, and the correlated colour temperature values are found to be in the warm white range: 3260-4000 K.

View Article: PubMed Central - PubMed

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

ABSTRACT
In this work we demonstrate by photoluminescence studies white light emission from a monolithic InGaN/GaN single quantum well structure grown by metal organic chemical vapour deposition. As-grown and thermally annealed samples at high temperature (1000 °C, 1100 °C and 1200 °C) and high pressure (1.1 GPa) were analysed by spectroscopic techniques, and the annealing effect on the photoluminescence is deeply explored. Under laser excitation of 3.8 eV at room temperature, the as-grown structure exhibits two main emission bands: a yellow band peaked at 2.14 eV and a blue band peaked at 2.8 eV resulting in white light perception. Interestingly, the stability of the white light is preserved after annealing at the lowest temperature (1000 °C), but suppressed for higher temperatures due to a deterioration of the blue quantum well emission. Moreover, the control of the yellow/blue bands intensity ratio, responsible for the white colour coordinate temperatures, could be achieved after annealing at 1000 °C. The room temperature white emission is studied as a function of incident power density, and the correlated colour temperature values are found to be in the warm white range: 3260-4000 K.

No MeSH data available.


Chromaticity coordinates (CIE 1931) of the as-grown and HTHP-1000 samples for the different photon excitation power densities.Inset: correlated colour temperatures (CCT) of the perceived white photoluminescence, as function of power density.
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f5: Chromaticity coordinates (CIE 1931) of the as-grown and HTHP-1000 samples for the different photon excitation power densities.Inset: correlated colour temperatures (CCT) of the perceived white photoluminescence, as function of power density.

Mentions: Room temperature PL spectra versus laser power density for the as-grown and HTHP annealed at 1000 °C (HTHP-1000) QW structures were used to calculate the Commission Internationale de l’Eclairage (CIE 1931) chromaticity coordinates and the corresponding CCT (calculated after Ref. 37) of the perceived white light emission. The resulting chromaticity diagram is shown in Fig. 5, with the inset presenting the CCT as function of photon excitation power density. The CIE and CCT results are summarized in Table I. It can be seen from the chromaticity diagram, that when the laser power density increases, the CIE coordinates move from (0.37, 0.36) up to (0.43, 0.45), describing a white emission change from warm white to cooler white as expected due to the YB PL saturation. This can also be seen in the inset of Fig. 5 which shows an increase of CCT from 3260 up to 4000 K by increasing the laser power density. HTHP annealing studies on InGaN/GaN MQWs have already demonstrated that the structure and excitonic well recombination is stable after post-growth heat treatments. Particularly, in the case of the green QW emission, a high stability of the QW recombination was found after HTHP annealing at 1400 °C35. In the case of the investigated structures, the BB PL from the active layer still persists after a HTHP annealing up to 1000 °C. As such, the HTHP treatment constitutes an effective tool to tune the YB/BB PL intensity ratio in the QW structure.


Photoluminescence studies of a perceived white light emission from a monolithic InGaN/GaN quantum well structure.

Ben-Sedrine N, Esteves TC, Rodrigues J, Rino L, Correia MR, Sequeira MC, Neves AJ, Alves E, Bockowski M, Edwards PR, O'Donnell KP, Lorenz K, Monteiro T - Sci Rep (2015)

Chromaticity coordinates (CIE 1931) of the as-grown and HTHP-1000 samples for the different photon excitation power densities.Inset: correlated colour temperatures (CCT) of the perceived white photoluminescence, as function of power density.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4559898&req=5

f5: Chromaticity coordinates (CIE 1931) of the as-grown and HTHP-1000 samples for the different photon excitation power densities.Inset: correlated colour temperatures (CCT) of the perceived white photoluminescence, as function of power density.
Mentions: Room temperature PL spectra versus laser power density for the as-grown and HTHP annealed at 1000 °C (HTHP-1000) QW structures were used to calculate the Commission Internationale de l’Eclairage (CIE 1931) chromaticity coordinates and the corresponding CCT (calculated after Ref. 37) of the perceived white light emission. The resulting chromaticity diagram is shown in Fig. 5, with the inset presenting the CCT as function of photon excitation power density. The CIE and CCT results are summarized in Table I. It can be seen from the chromaticity diagram, that when the laser power density increases, the CIE coordinates move from (0.37, 0.36) up to (0.43, 0.45), describing a white emission change from warm white to cooler white as expected due to the YB PL saturation. This can also be seen in the inset of Fig. 5 which shows an increase of CCT from 3260 up to 4000 K by increasing the laser power density. HTHP annealing studies on InGaN/GaN MQWs have already demonstrated that the structure and excitonic well recombination is stable after post-growth heat treatments. Particularly, in the case of the green QW emission, a high stability of the QW recombination was found after HTHP annealing at 1400 °C35. In the case of the investigated structures, the BB PL from the active layer still persists after a HTHP annealing up to 1000 °C. As such, the HTHP treatment constitutes an effective tool to tune the YB/BB PL intensity ratio in the QW structure.

Bottom Line: As-grown and thermally annealed samples at high temperature (1000 °C, 1100 °C and 1200 °C) and high pressure (1.1 GPa) were analysed by spectroscopic techniques, and the annealing effect on the photoluminescence is deeply explored.Under laser excitation of 3.8 eV at room temperature, the as-grown structure exhibits two main emission bands: a yellow band peaked at 2.14 eV and a blue band peaked at 2.8 eV resulting in white light perception.The room temperature white emission is studied as a function of incident power density, and the correlated colour temperature values are found to be in the warm white range: 3260-4000 K.

View Article: PubMed Central - PubMed

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

ABSTRACT
In this work we demonstrate by photoluminescence studies white light emission from a monolithic InGaN/GaN single quantum well structure grown by metal organic chemical vapour deposition. As-grown and thermally annealed samples at high temperature (1000 °C, 1100 °C and 1200 °C) and high pressure (1.1 GPa) were analysed by spectroscopic techniques, and the annealing effect on the photoluminescence is deeply explored. Under laser excitation of 3.8 eV at room temperature, the as-grown structure exhibits two main emission bands: a yellow band peaked at 2.14 eV and a blue band peaked at 2.8 eV resulting in white light perception. Interestingly, the stability of the white light is preserved after annealing at the lowest temperature (1000 °C), but suppressed for higher temperatures due to a deterioration of the blue quantum well emission. Moreover, the control of the yellow/blue bands intensity ratio, responsible for the white colour coordinate temperatures, could be achieved after annealing at 1000 °C. The room temperature white emission is studied as a function of incident power density, and the correlated colour temperature values are found to be in the warm white range: 3260-4000 K.

No MeSH data available.