Isoelectronic Trap Like Luminescence Centers Of Ingan

Kanie, Hisashi; Koami, Hikari; Kawano, Teruhiko; Totsuka, T.

doi:10.1557/proc-482-731

Cited by 4 publications

(2 citation statements)

References 15 publications

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“…InGaN shows several characteristic emission properties. Double or multi peaked CL spectra with a separation of more than 10 nm were observed from the InGaN microcrystals [12,13]. A similar double peaked CL spectrum is observed from the epitaxial InGaN layer grown thicker than the critical thickness on the GaN buffer layer [10,11].…”

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Excitation energy transfer between luminescent centers of microcrystalline InGaN

Kanie

Yoshimura

2003

phys. stat. sol. (c)

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PACS 61.72.Ji, 71.55.Eq, 78.60.Hk InGaN microcrystals were grown by nitridation of gallium and indium sulfide. Cathodoluminescence (CL) image observation of InGaN microcrystals at room temperature was performed under a scanning electron microscope at 3-5 kV with a beam diameter of 10 nm equipped with a monochromator. Highspatial-resolution monochromatic CL images composited with secondary electron microscope images showed each facet has uniform but different CL spectra, such as single or double peaked spectra at 420 and 460 nm. From the width of a dark zone and bright zone at the fringe of the facet in the monochromatic CL images taken at the two wavelengths the length of the excitation energy transfer was estimated as the diffusion length of the excited carriers. The ratios of the lifetimes of the radiative and nonradiative process of the excited carriers are calculated from the estimated diffusion lengths. , so the theoretical limit of efficiency ranges from 60 to 68% at the highest, though empirically it has been reported that the highest theoretical efficiency is about 38% [2]. To improve the efficiency we must understand the properties, such as density, cross section, lifetime and the atomic structure of the radiative and nonradiative centers in addition to the emissin mechanism [3,4]. The lifetime of excited carriers may be calculated by the diffusion length estimated from the width of a dark zone (energy transfer to the nonradiative center) in CL images [5,6]. InGaN shows several characteristic emission properties. Double or multi peaked CL spectra with a separation of more than 10 nm were observed from the InGaN microcrystals [12,13]. A similar double peaked CL spectrum is observed from the epitaxial InGaN layer grown thicker than the critical thickness on the GaN buffer layer [10,11]. The depth profile of CL spectrum is surveyed with an increase in the acceleration voltage and the double peaked spectra are measured and explained not by the quantum dot like In rich or phase separation region [3,4], but by the stress relaxation toward the growth direction confirmed by X-ray diffraction [10]. The low energy luminescence is attributed to the relaxed InGaN layer near the surface and the higher energy luminescence to the coherent InGaN layer on the GaN buffer layer, although X-ray diffraction data showed that the InGaN layer relaxed with the In content keeping at the same level [10]. The luminescence center has feature of a deep localized center, such as a broad bandwidth. The emission process of the double peaked CL spectra may be universal for InGaN. As the emission process of InGaN microcrystals is not well understood, however, we tentatively assign the observed luminescence peaking at 420 nm to a luminescence center at 420 nm and at 460 nm to the cen-

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confidence: 62%

Excitation energy transfer between luminescent centers of microcrystalline InGaN

Kanie

Yoshimura

2003

phys. stat. sol. (c)

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“…We developed synthesis of InGaN powder crystals as low voltage phosphors for FEDs [1]. There are three challenges from the start, high yield, more uniformity, and high CL efficiency of blue InGaN phosphors.…”

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confidence: 99%

InGaN blue cathodoluminescence phosphors synthesized with long reaction time in a new reactor

Kanie

Kobayashi

Yuji

2006

Phys. Status Solidi (c)

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InGaN microcrystals were grown by two-stage growth method for 10 hours in a new reactor without clogging an exhaust tube by fine particles. Obtained InGaN showed double peaked cathodoluminescence spectra, violet peak at 385-389 nm and blue at 438-444 nm when excited at 5-15 kV. The uniformity of the blue emission spectra among the crystals were improved for those grown for the 10-hour reaction time. The yields of emissive GaN and InGaN crystals were not improved. The compatibility of the position of the violet band of the InGaN crystals to that of the GaN crystals and the resemblance of morphology of the GaN and InGaN crystals imply the growth of InGaN on GaN facets in two-stage growth. The cause of the deterioration of the CL efficiency of the grown InGaN crystals at a low acceleration voltage was discussed.

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Nitride Phosphors for Low Voltage Cathodoluminescence Devices

et al. 2000

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Undoped and Zn doped InGaN microcrystals were synthesized by a two-step method. The InGaN microcrystals have a wurtzite structure and brownish body color. The InGaN samples prepared at 900°C did not contain a metal In phase. The InGaN:Zn microcrystals showed blue photoluminescence (PL) at 77K different from that of GaN:Zn. Reflectivity and photoluminescence excitation (PLE) measurement showed that the fundamental absorption edge of the InGaN:Zn phosphors is 3.47 eV, which implies that the In content in the InGaN:Zn phosphors is less than 0.2%. GaN:Zn and InGaN:Zn showed a Zn related PLE peak at 3.34 eV. InGaN and InGaN:Zn showed an In related PLE peak at 3.14 eV. When the InGaN:Zn samples were selectively excited at 3.15 eV, an In-related emission band centered at 2.2 eV emerged. The InGaN:Zn phosphors mounted on vacuum fluorescent displays (VFDs) showed room-temperature blue cathodoluminescence (CL) and the CL peak shifted slightly toward the low energy compared to that of the GaN:Zn phosphors because of the superimposed In related band. The InGaN:Zn phosphors had a luminance of 50 cd/m2 and a luminance efficiency of 0.03 lm/W at an anode voltage of 50 V.

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Isoelectronic Trap Like Luminescence Centers Of Ingan

Cited by 4 publications

References 15 publications

Excitation energy transfer between luminescent centers of microcrystalline InGaN

Excitation energy transfer between luminescent centers of microcrystalline InGaN

InGaN blue cathodoluminescence phosphors synthesized with long reaction time in a new reactor

Nitride Phosphors for Low Voltage Cathodoluminescence Devices

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