Self-assembled ZnO nano-crystals and exciton lasing at room temperature

Tang, Zikang; Kawasaki, Masashi; Ohtomo, Akira; Koinuma, Hideomi; Segawa, Y.

doi:10.1016/j.jcrysgro.2005.10.062

Cited by 85 publications

(72 citation statements)

References 32 publications

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“…This was for layers grown by laser molecular beam epitaxy [4]. Other work reported gains of 340 cm -1 [8], 300 cm -1 [5], 160 cm -1 [2] and 40 cm -1 [3]. Zhang et al also reported the lowest optical losses for ZnO thin films, of 68 cm -1 [4].…”

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confidence: 90%

“…Higher optical gain, for instance, allows amplification with shorter active-medium lengths, while reduced losses allow lower lasing thresholds. In the literature, stimulated emission has been observed from the surface [2,3], from the edge [4,5] and even via random lasing [6,7] for ZnO thin films. Zhang et al [4] reported the highest optical gain value for ZnO films, so far, of 571 cm -1 .…”

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confidence: 99%

“…By fitting the curve of I ASE (,L) versus L, Fig. 3-a, with the above equation in the unsaturated region, the gain is obtained [5,22]. Figure 3-a shows the recorded I ASE (, L) versus L at 391 nm and 394 nm (corresponding to the P-band and Nband, respectively).…”

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confidence: 99%

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Stimulated emission from ZnO thin films with high optical gain and low loss

Gadallah¹,

Nomenyo²,

Couteau

et al. 2013

Applied Physics Letters

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Abstract:Stimulated surface-and edge-emission were investigated for ZnO thin films grown epitaxially by pulsed laser deposition. The lasing threshold was 0.32 MW/cm 2 for surface pumping and 0.5 MW/cm 2 for edge pumping, which is significantly lower than thresholds observed previously. A modified variable stripe length method was used to measure the gain, which was 1369 cm -1 for Nband emission. Losses were measured using the shifting excitation spot method and values of 6.2 cm -1 and 6.3 cm -1 were found for the N-band and P-band, respectively. The measured gain and loss were the highest and lowest (respectively) ever reported for ZnO films.

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confidence: 90%

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confidence: 99%

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Stimulated emission from ZnO thin films with high optical gain and low loss

Gadallah¹,

Nomenyo²,

Couteau

et al. 2013

Applied Physics Letters

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“…The PL spectra of these films consist of two emission bands, one in the UV region and other in the visible region. It is well known that UV emission peaks originate from the recombination of free excitons through an exciton-exciton collision process corresponding to near band edge (NBE) emission of wide band gap ZnO (Tang et al 2006). The impurities and structural defects, such as oxygen and zinc vacancies and interstitials give rise to visible emission peaks (Mei et al 2004).…”

Section: Raman and Photoluminescence Studiesmentioning

confidence: 99%

“…It has a rich family of unique and peculiar nanostructures (Kong and Wang 2004;SchmidtMende and MacManus-Driscoll 2007). Nanostructures with different morphologies such as wires, rods, tubes, belts, plates, flowers and tetrapods have been synthesized by different physical and chemical vapor deposition techniques (Lao et al 2002;Newton and Warburton 2007;Tang et al 2006;Umar et al 2005;Liu et al 2004;Sun et al 2004;Kim et al 2004). Due to larger surface area, sensors and solar cells fabricated using ZnO flower-like nanostructured films exhibited higher sensitivity and efficiency.…”

Section: Introductionmentioning

confidence: 99%

Deposition of ZnO nanostructured film at room temperature on glass substrates by activated reactive evaporation

2013

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ZnO nanostructured films were deposited on glass substrates at room temperature by activated reactive evaporation technique. Thermal evaporation of zinc at high deposition rate in presence of oxygen plasma resulted in deposition of ZnO nanostructured film with different flower-like morphologies on glass substrates. The structural and morphological properties of these nanostructured films were studied by XRD, SEM and TEM. A gas phase growth mechanism has been proposed for the formation of nanostructures. The room temperature photoluminescence spectra of these films exhibited weak ultraviolet (UV) and strong broad visible emission peaks. Further, the position of visible emission peak is found to vary with morphology of the grown nanostructured films. Photocurrent measurements indicated that these ZnO nanostructured films show high sensitivity to UV light, and hence can be used as efficient UV photodetectors.

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Electro‐Optic Effect of ZnO Microcavity and Active Dynamic Lasing Mode Modulation

Zhao

Liu

et al. 2022

Advanced Optical Materials

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of the medium. Over the past few decades, various methods have been applied to achieve the modulation of lasing, such as building distributed Bragg reflection (DBR) [1] or distributed feedback (DFB) [2] structures, changing the cavity size, [3] and utilizing self-absorption effects, [4,5] Burstein-Moss (BM) effect [6] or Vernier effect. [7] The dynamic modulation of lasing by using piezoelectric [8,9] and electrooptic effects [10] were used to modulate the refractive index of the crystal. However, the electrical methods are more conducive to miniaturizing and integrating than the mechanical methods, which requires additional stressing devices.Electro-optic effect, as a phenomenon of electric field induced refractive index variation of electro-optic crystal, including 1st and 2nd order electro-optical effects (so-called the Pockels effect and Kerr electro-optic effect), has been commonly used to modulate the lasing modes. However, in general, lasing is resonated and amplified in a gain cavity and the modes are regulated externally in different materials and spaces. In the other word, the modulation is usually operated passively. It will be great favorable for optoelectronic integration if the gain medium itself has electrooptic effect so that plays both roles as the optical microcavity for resonance and electro-optic response for lasing mode modulation. ZnO with a non-centrosymmetric hexagonal structure has been demonstrated nonlinear optics in films. [11,12] Meanwhile, it has attracted considerable attention as an excellent gain media for UV lasing due to its wide direct bandgap and lager exciton binding energy. [13][14][15] This indicates a good candidate for functional integration of lasing generation and dynamic modulation in the ZnO microcavity.In this paper, an individual ZnO hexagonal microrod with high crystalline quality and smooth surface was utilized as a UV lasing microcavity, while an electric field was applied perpendicularly and parallelly to the C-axis of the microcrystal, respectively. The optically pumped lasing modes were modulated dynamically by changing the applied voltage. Corresponding to perpendicular and parallel direction of the electric field, the refractive index variation presents a linear and quadratic increase tendency with the electric field strength, resulted from Pockels and Kerr electro-optic effect, respectively. Based on the systematic analysis, the 1st and 2nd order electrooptical coefficients and modulation speed were estimated. This

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Self-assembled ZnO nano-crystals and exciton lasing at room temperature

Cited by 85 publications

References 32 publications

Stimulated emission from ZnO thin films with high optical gain and low loss

Stimulated emission from ZnO thin films with high optical gain and low loss

Deposition of ZnO nanostructured film at room temperature on glass substrates by activated reactive evaporation

Electro‐Optic Effect of ZnO Microcavity and Active Dynamic Lasing Mode Modulation

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