Origin of efficient luminescence from GaN:Eu3+ epitaxial films revealed by microscopic photoluminescence imaging spectroscopy

Ishizumi, Atsushi; Sawahata, Junji; Akimoto, Katsuhiro; Kanemitsu, Yoshihiko

doi:10.1063/1.2385180

Cited by 13 publications

(7 citation statements)

References 15 publications

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“…The intensity of the PL due to the Eu 3+ ions is sensitive to the monitored position; the several bright spots and dark area are clearly observed. Similar inhomogeneous PL intensity images are also obtained at room temperature [14]. In our microscopic PL imaging spectroscopy experiments at room temperature [14], it has been concluded that the intensity of the Eu 3+ ions is sensitive to local environment of Eu 3+ ions and that the Eu 3+ ions exhibit efficient luminescence when they are incorporated into distorted Ga lattice sites around the point defects and dislocations introduced by the doping of Eu 3+ ions.…”

Section: Resultssupporting

confidence: 65%

“…Space-resolved photoluminescence (PL) spectroscopy is one of the most useful methods for understanding of the nature of impurity luminescence and energy transfer mechanism in impurity-doped semiconductors [12][13][14]. In the previous report [14], we have revealed that the efficient red luminescence is attributed to the Eu 3+ ions located around point defects and * Corresponding author.…”

Section: Introductionmentioning

confidence: 98%

“…In the previous report [14], we have revealed that the efficient red luminescence is attributed to the Eu 3+ ions located around point defects and * Corresponding author. dislocations in the GaN:Eu 3+ crystals.…”

Section: Introductionmentioning

confidence: 98%

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Site-dependent Eu3+ luminescence in GaN:Eu3+ epitaxial films studied by microscopic photoluminescence spectroscopy

Ishizumi

Sawahata

Akimoto

et al. 2008

Materials Science and Engineering: B

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Section: Resultssupporting

confidence: 65%

Section: Introductionmentioning

confidence: 98%

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Site-dependent Eu3+ luminescence in GaN:Eu3+ epitaxial films studied by microscopic photoluminescence spectroscopy

Ishizumi

Sawahata

Akimoto

et al. 2008

Materials Science and Engineering: B

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“…Thus, the incorporation of Eu ions inside the GaN NCs' core changes their lattice constant, which should induce strain, 23 which, in turn, creates more defect states ͑increasing visible intensity͒. Moreover, for the GaN film, Ishizumi et al 24 have observed that Eu 3+ -ion doping induces stacking faults and twins with the dislocations in the GaN host crystal and that the distortion of the crystal lattice occurs over the entire GaN:Eu 3+ films as a result of these dislocations.…”

Section: K34mentioning

confidence: 97%

Influence of Europium Concentration on Optical and Structural Properties of Nanocrystalline GaN:Eu[sup 3+] Powder

Podhorodecki

Nyk

Zatryb

et al. 2009

Electrochem. Solid-State Lett.

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In this work, GaN nanocrystals doped by europium ͑III͒ ions at different concentrations have been synthesized by modified nitridation method at 1050°C temperature. From X-ray diffraction spectra, it has been found that the size of nanocrystals strongly depends on the dopant concentration in a nonlinear way and varying from ϳ20 up to 35 nm when the europium concentration varies from 0.5 up to 2 mol %. Moreover, it has been found that obtained nanocrystals are characterized by two main emission bands, one related to GaN core ͑ϳ364 nm͒ and the second to surface/defect states ͑ϳ600 nm͒. It has been shown that the relative intensity of these bands varies with changing of the europium concentration due to changes of GaN nanocrystals surface-tovolume ratio.In recent years, the study of semiconductor nanocrystals ͑NCs͒ generates intense interest because, at this scale, materials exhibit many properties that cannot be found in their bulk counterparts. It is mostly due to the strong dependence of the energy bandgap on the grain size and huge surface-to-volume ͑S/V͒ ratio. For these reasons, many technological and scientific activities have been focused on controlling the size of the NCs and their surface properties. Recently, GaN has become a material of particular interest because of its useful electrical properties and the direct bandedge in the UV region.Thus, the nanocrystalline GaN should also be characterized by the emission at UV range, but also this wide bandgap enables the doping of these NCs by the different rare-earth ͑RE͒ ions, emitting at both IR and visible. It makes this material more suitable for many interesting optoelectronic 1 and biological applications 2 than, i.e., the Si or CdSe matrix. Recently, it has been shown by us 3,4 and other authors 5-8 that this kind of nanostructured material ͑GaN:Eu͒ can be promising for red emission. The doping of NCs can also have other interesting influences on the NCs optical and structural properties. Recently, Du et al. 9 have pointed out that the diffusion through the NCs is strongly suppressed, and the only viable alternative is the dopant adsorption on the surface, at a location that corresponds to a bulk lattice site when overgrown by additional material. Moreover, authors have suggested that the successful doping of NCs depends mainly on three factors: surface morphology, nanocrystal shape, and surfactants in the growth solution. 10 Thus, the doping of NCs by RE ions, which easily form the oxide phase, could strongly modify the structural properties of NCs because overgrowth becomes less probable in the growth direction, where the RE ions have been attached.It is well known that the optical properties of the nanocrystalline materials vary with their size/shape and surface properties. Thus, a possible change in the NCs size, shape, or surface morphology cannot be neglected, especially in the NCs size regime corresponding to the appearance of the strong quantum confinement.Nevertheless, most investigations in the field of NCs doped by RE focus on the optical prop...

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“…This also applies for solar cells, and simultaneous observation of PC and PL, with extension to time-resolved or microscopic techniques have been performed successfully [21]- [26]. For excitation we use two wavelength tunable sources, and an infrared laser diode with a fixed wavelength.…”

Section: Sample Structure and Experimental Setupmentioning

confidence: 98%

Identification of trap states for two-step two-photon-absorption processes in InAs quantum structures for intermediate-band solar cells

Tex

Kamiya

Kanemitsu

2014

2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)

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Intermediate bands bear trap and recombination centers for carriers generated in other energy levels. Assessment of recombination centers is important for achieving efficient carrier generation. We measure the photocurrent (PC) originating from InAs quantum structures embedded in an undoped (Al)GaAs matrix due to excitation with multiple tunable beams. With an infrared light excitation the influence of trapping or recombination on the quantum dot PC generation efficiency via two-step two-photon-absorption processes is evaluated.

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Origin of efficient luminescence from GaN:Eu3+ epitaxial films revealed by microscopic photoluminescence imaging spectroscopy

Cited by 13 publications

References 15 publications

Site-dependent Eu3+ luminescence in GaN:Eu3+ epitaxial films studied by microscopic photoluminescence spectroscopy

Site-dependent Eu3+ luminescence in GaN:Eu3+ epitaxial films studied by microscopic photoluminescence spectroscopy

Influence of Europium Concentration on Optical and Structural Properties of Nanocrystalline GaN:Eu[sup 3+] Powder

Identification of trap states for two-step two-photon-absorption processes in InAs quantum structures for intermediate-band solar cells

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