Long-lasting photoluminescence in freestanding GaN templates

Reshchikov, M. A.; Iqbal, M. Zafar; Morkoç̌, H.; Park, S. S.; Lee, K. Y.

doi:10.1063/1.1589194

Cited by 15 publications

(28 citation statements)

References 11 publications

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“…The GL band (maximum at about 2.45 eV) rapidly transforms into the YL band (2.2 eV) after about 10 À4 s following the excitation pulse. The non-exponential decays of PL at 15 K have been attributed to the donor-acceptor-pair (DAP) transitions involving a shallow donor and different acceptors, whereas the transformation of the GL into YL has been attributed to the manifestation of two charge states of the same acceptor, presumably V Ga O N complex [3].…”

Section: Methodsmentioning

confidence: 98%

“…Previously, we proposed that the dominant defect responsible for the yellow (YL) and green luminescence (GL) bands in freestanding GaN templates is a deep acceptor, presumably a gallium vacancy-oxygen complex (V Ga O N ) in the 0/À and À/2À charge states [2]. Time-resolved PL (TR-PL) study at low temperatures revealed a transformation of the GL band into the YL band and very slow non-exponential decay of the latter [3]. In the present work, we have studied the effect of temperature on the TR-PL in the freestanding GaN.…”

Section: Introductionmentioning

confidence: 99%

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Unusual properties of the dominant acceptor in freestanding GaN

Reshchikov¹,

Park²,

Lee³

et al. 2003

Physica B: Condensed Matter

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Section: Methodsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Unusual properties of the dominant acceptor in freestanding GaN

Reshchikov¹,

Park²,

Lee³

et al. 2003

Physica B: Condensed Matter

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“…Сarriers captured in QW reveal long-lived kinetics in microsecond scale [5]. Moreover PL signal from electron hole pair could be clearly detected up to tens of second after excitation due to non-exponential decay of carrier concentration [6,7]. Bleaching effect could be reduced by lowering of Al percentage in Al Ga 1− As QW barriers down to few percent [8].…”

Section: Introductionmentioning

confidence: 80%

Bleaching compensation in GaAs/AlGaAs quantum wells by above-barrier illumination

Solovev

Kapitonov

Davydov

et al. 2017

J. Phys.: Conf. Ser.

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Abstract. We report an experimental study of the nonlinear response of single GaAs/AlGaAs quantum well. It was shown that bleaching effect manifested as reversible exciton spectral lines broadening can be suppressed by additional above-barrier illumination. IntroductionOne of the most promising alternatives to current silicon-based electronics is the information processing in purely optical way [1][2][3]. Exciton and excitonic complexes in A3B5 nanostructures strongly interact with light due to the relatively large oscillator strength and could serve as a physical model of two-level system that draws special attention in the area of optical computing. However bleaching effect manifested as reversible exciton spectral line broadening limits usefulness of GaAs/AlGaAs structures in informational photonics.Earlier it was shown that at relatively weak and intermediate intensities exciton bleaching is observed while spectrally integrated peak intensity in the absorption spectrum remains the same [4]. The main mechanism of bleaching is said to be broadening of the exciton line induced by scattering of excitons on carriers and exciton-carriers complexes. Сarriers captured in QW reveal long-lived kinetics in microsecond scale [5]. Moreover PL signal from electron hole pair could be clearly detected up to tens of second after excitation due to non-exponential decay of carrier concentration [6,7]. Bleaching effect could be reduced by lowering of Al percentage in Al Ga 1− As QW barriers down to few percent [8].Carriers could be observed even in nominally undoped quantum wells (QWs) grown by Molecular Beam Epitaxy (MBE) due to the unintentional doping. Presence of carriers in QW leads to the formation of a peak in the photoluminescence (PL) spectrum at energies below exciton recombination line [9] . This peak corresponds to the exction-carrier bound state -trion. Additional optical pump could lead either to the buildup or to the reduction of charge carriers concentration in QW depending on the pump spectral position relative to the band gap [10]. Alterations in carriers concentration or even in their sign [11] may be revealed by analysis of opposing changes in trion and exciton peak amplitudes in PL.PL spectroscopy is generally used for detection of such charged exciton complexes [5,[9][10][11]. Still it could not give the full picture of the exciton dynamics due to the difficulty of the factorization of the exciton resonance width. We propose the Brewster angle reflection

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“…Indeed, the Si doping has been found to be able to suppress the formation of point defects in GaN and prevent from the potential irregularities at the domain boundaries in Si doped layers [21]. Thus, we point out that the defects near the surface play an important role in emission mechanisms in GaN thin films [11] and are responsible for the inefficient band-edge emission observed in the PL spectra.…”

mentioning

confidence: 92%

“…It was found that the effect of surface layer is closely related to the optical properties of GaN upon annealing [8] or after surface treatment [9,10]. Besides, the existence of the surface state has been considered as the possible reason for the observation of persistent photoluminescence (PL) in GaN [11]. Recently, there have been several reports concerning the electric force microscopy (EFM) on GaN samples [12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Investigation of surface properties of Si-doped GaN films by electric force microscopy and photoluminescence

Lin

Chen

2004

Solid State Communications

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Results of the electric force microscopy (EFM) and photoluminescence (PL) measurements in a set of Si-doped GaN films are presented. The EFM measurements indicate that substantial surface states exist in GaN thin films and the density of surface states is reduced with the Si doping concentration. It is found that this result strongly correlates with the optical properties of the epifilms. We show that the ratio of near-band edge luminescence of the front-side and back-side PL spectra increases with the doping concentration. This behavior manifests the effects of the surface states on the luminescent properties of GaN. Our investigation therefore not only shows the important role of surface states on the optical properties of GaN, but it also reveals that the combination of EFM and optical techniques is a very powerful way to understand the physical properties of a thin film. GaN and related heterostructures are now well established as materials of importance to both science and technology for the development of high-temperature microelectronics, light emitters, and detectors [1,2]. Great attention was paid to the emission mechanism in the active layer of the emitting devices, both experimentally [3,4] and theoretically [5,6]. On the other hand, fewer investigations have focused on surface properties of GaN [7 -11], which are very important to the reliable performance for the device applications. The n-/p-type nature of GaN and InGaN layers, and their related band bendings in surface and interfaces have been studied by contactless electroreflectance [7]. It was found that the effect of surface layer is closely related to the optical properties of GaN upon annealing [8] or after surface treatment [9,10]. Besides, the existence of the surface state has been considered as the possible reason for the observation of persistent photoluminescence (PL) in GaN [11]. Recently, there have been several reports concerning the electric force microscopy (EFM) on GaN samples [12][13][14][15][16]. The surface potential mode of EFM is very sensitive to the polarity of the surface charge and has been used to image the inversion domains in GaN [12]. The piezoelectrically induced surface charge and potential can also be measured by EFM [13]. Accordingly, it is interesting to combine the EFM and optical techniques to study the surface properties of GaN, which are important to optical and electrical performance of GaN-based devices.In this article, we present EFM measurements and the results of the front-side and back-side PL measurements in a set of the Si-doped GaN epifilms. We demonstrate that EFM technique is able to detect the effect of Si doping on the surface properties of GaN films. Our experimental results reveal that substantial surface states exist in GaN epifilms, and they can be passivated by the Si incorporation. Our results also show that the defects near the surface are responsible for the inefficient band-edge emission observed in the PL spectra. In view of effects of surface related defects on the electrical a...

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Long-lasting photoluminescence in freestanding GaN templates

Cited by 15 publications

References 11 publications

Unusual properties of the dominant acceptor in freestanding GaN

Unusual properties of the dominant acceptor in freestanding GaN

Bleaching compensation in GaAs/AlGaAs quantum wells by above-barrier illumination

Investigation of surface properties of Si-doped GaN films by electric force microscopy and photoluminescence

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