Excitonic Mechanisms of Stimulated Emission in Low-Threshold ZnO Microrod Lasers with Whispering Gallery Modes

Тарасов, А. П.; Муслимов, А. Э.; Kanevsky, V. M.

doi:10.3390/ma15248723

Cited by 8 publications

(9 citation statements)

References 54 publications

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“…Until recently, it was widely believed that in WGM ZnO microstructures exhibiting intense redshift of the ASE/lasing band, optical gain is formed as a result of population inversion in the electron-hole plasma (EHP) [9,35,43,45]. However, in a recent study of low-threshold ZnO microrod lasers [46], we showed that the mechanism of redshifting gain at room temperature is exciton scattering on free electrons rather than an inverted EHP.…”

Section: Resultsmentioning

confidence: 83%

The Growth Mechanism, Luminescence, and Lasing of Polyhedral ZnO Microcrystals with Whispering-Gallery Modes

Zadorozhnaya,

Tarasov,

Kanevsky

2023

Photonics

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This work studies the features of the formation of isometric polyhedral ZnO microcrystals that provide stimulated emission and whispering-gallery-mode (WGM) lasing in the near-UV range. For this purpose, the growth stages of such crystals in the process of gas-transport synthesis and the luminescent properties of the structures obtained at each stage were investigated. It was shown that the growth of laser microcrystals begins with the formation of microspheroids with thin ZnO shells. Such spheroids exhibit mainly white luminescence with a small contribution of near-UV emission. Increasing the synthesis duration results in thickening and faceting of the spheroid shells, as well as a decrease in the contribution of the yellow–red component to the luminescence spectrum. At the same time, ZnO microcrystallites nucleate and grow inside the spheroids, using as a material the remains of a liquid zinc drop and oxygen entering the spheroids through their shells. Such growth conditions allow them to take on an equilibrium polyhedral shape. Eventually, upon destruction of the spheroid shell, a polyhedral ZnO microcrystal supporting WGMs is observed.

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Section: Resultsmentioning

confidence: 83%

The Growth Mechanism, Luminescence, and Lasing of Polyhedral ZnO Microcrystals with Whispering-Gallery Modes

Zadorozhnaya,

Tarasov,

Kanevsky

2023

Photonics

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“…most representative spectra are shown) registered under laser excitation with ρexc ≈ 25 kW/cm 2 (the case of the plasma-treated film was similar). The NBEL pattern at T ~ 80 K is typical for nominally undoped ZnO microcrystals at temperature [57][58][59]. In particular, three emission bands are clearly distinguishable (indicated as Ai in Figure 7, where i = 1, 2, 3) with the energies of 3.356, 3.311, and 3.234 eV (the corresponding wavelengths are 369.4, 374.5, 383.4 nm).…”

Section: Resultsmentioning

confidence: 92%

“…In addition, the films' NBEL pattern is typical for microcrystalline ZnO at low temperatures and low excitation intensities. In this case, we can use the data on E g (T) or E X (T) for bulk or microcrystalline ZnO to interpret the luminescence mechanisms of the studied samples at various temperatures, including RT [59]. In particular, E X (T) obtained for a bulk ZnO crystal in [57], valid for microcrystalline ZnO [59], is shown in Figure 7b as a solid line.…”

Section: Resultsmentioning

confidence: 99%

“…In this case, we can use the data on E g (T) or E X (T) for bulk or microcrystalline ZnO to interpret the luminescence mechanisms of the studied samples at various temperatures, including RT [59]. In particular, E X (T) obtained for a bulk ZnO crystal in [57], valid for microcrystalline ZnO [59], is shown in Figure 7b as a solid line. In Figure 7b, the temperature behavior for the energies of the X-LO and X-2LO bands is also plotted, according to the expression [58] Photonics 2023, 10, 1354 10 of 15…”

Section: Resultsmentioning

confidence: 99%

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Effect of Plasma Treatment on the Luminescent and Scintillation Properties of Thick ZnO Films Fabricated by Sputtering of a Hot Ceramic Target

Tarasov,

Ismailov,

Gadzhiev

et al. 2023

Photonics

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The paper presents the results of a comprehensive study of the structural-phase composition, morphology, optical, luminescent, and scintillation characteristics of thick ZnO films fabricated by magnetron sputtering. By using a hot ceramic target, extremely rapid growth (~50 µm/h) of ZnO microfilms more than 100 µm thick was performed, which is an advantage for the industrial production of scintillation detectors. The effects of post-growth treatment of the fabricated films in low-temperature plasma were studied and a significant improvement in their crystalline and optical quality was shown. As a result, the films exhibit intense near-band-edge luminescence in the near-UV region with a decay time of <1 ns. Plasma treatment also allowed to significantly weaken the visible defect luminescence excited in the near-surface regions of the films. A study of the luminescence mechanisms in the synthesized films revealed that their near-band-edge emission at room temperature is formed by phonon replicas of free exciton recombination emission. Particularly, the first phonon replica plays the main role in the case of optical excitation, while upon X-ray excitation, the second phonon replica dominates. It was also shown that the green band peaking at ~510 nm (2.43 eV) is due to surface emission centers, while longer wavelength (>550 nm) green-yellow emission originates mainly from bulk parts of the films.

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“…7 shows the spectrum of E g (eV) vs, calcination temperature (°C) of all the thin solid lms. Reports of the optical behavior of the fundamental electronic transition CB→CV of ZnO, which is often attributed to direct recombination in the inverted electron-hole plasma [33], identi ed and assigned to the phenomenon of recombination of energetic excitons are tightly bound and dominate the optical response even at room temperature [34].…”

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confidence: 99%

Thin films ZnO-QDs Synthesis applying simultaneously the techniques of colloidal synthesis and sol gel and phenomenon at Zn2+→Zn3+ + e- charge transfer, applied to Shottky diode.

Garrido

Portillo

Ramírez

et al. 2023

Preprint

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The Zinc Oxide and the Quantum dots of ZnO (ZnO-QD´s) in thin solid films were deposited by dropwise method on glass substrates and calcined in air atmosphere at temperatures of 60 °C, 100 °C, 140 °C, 160 °C and 210 °C, respectively. The samples are examined applying the techniques: Scanning Electron Microscopy (SEM), x-Ray Diffraction (XRD), Fourier transforms in the Infrared (FTIR), Photoluminescence (PL), Transmittance (%T), and absorbance (α). Tauc model, the band gap (Eg) energy is evaluated. The electrical measurements of Current-Voltage (I-V), the concentration of charge carriers, mobility and Resistance, are registered by Hall Effect. The morphology of the layers shows a structural configuration with stacked compact plates and flakes-like of crystalline conglomerates with a fibrous appearance. The films show a Wurtzite-type crystalline phase according to the XRD diffractograms. The grain size increased by ~3.6-26.1 nm. The dislocation density (δ) presents a gradual increase with the calcination temperature δ(lines/m2) ~1.57 x 1015-2.22 x 1015. On FT-IR spectroscopy analysis, various vibrational bands are associated with the CO32 ion and by-products generated by the hydrolysis of zinc acetate di-hydrate discussed. The Eg undergoes oscillatory and disorderly shifting towards higher photon energy, caused by faults at crystalline lattice of Eg ~3.7-3.87 eV. In optical analysis, the discontinuity located at UV-Vis region is associated in principle at Zn2+→Zn3+ + e- charge transfer. PL spectra at UV-Vis region records the emission bands with different relative intensity. The asymmetric Gaussian curve is associated with intrinsic defects in the crystal lattice. The deconvolution of the Gaussian curve generates different emission bands assigned to: red (RE) at ~770 nm, blue (BE), green (GE) at ~492-520 nm and yellow (YE) at ~570-600 nm. The study and systematic construction of the Schottky diode is done by placing the corresponding thin film on ITO, then PEDOT: PSS was placed, then the silver contact and finally the p-n junction was identified, obtaining better results than QD's ZnO in the Shottky diode plot.

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Excitonic Mechanisms of Stimulated Emission in Low-Threshold ZnO Microrod Lasers with Whispering Gallery Modes

Cited by 8 publications

References 54 publications

The Growth Mechanism, Luminescence, and Lasing of Polyhedral ZnO Microcrystals with Whispering-Gallery Modes

The Growth Mechanism, Luminescence, and Lasing of Polyhedral ZnO Microcrystals with Whispering-Gallery Modes

Effect of Plasma Treatment on the Luminescent and Scintillation Properties of Thick ZnO Films Fabricated by Sputtering of a Hot Ceramic Target

Thin films ZnO-QDs Synthesis applying simultaneously the techniques of colloidal synthesis and sol gel and phenomenon at Zn2+→Zn3+ + e- charge transfer, applied to Shottky diode.

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