Self-assembling GaN quantum dots on Al<i>x</i>Ga1−<i>x</i>N surfaces using a surfactant

Tanaka, Satoru; Iwai, Sohachi; Aoyagi, Yoshinobu

doi:10.1063/1.117830

Cited by 281 publications

(162 citation statements)

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“…As a possible origin, Ruminov et al suggested that Si mostly affects the dislocation structure during the GaN growth, perhaps by changing the atom mobility and the number of growth islands at the initial stage of the growth, and/or changing the dislocation mobility. Aoyagi and co-workers [23][24][25] have used the influence of silicon on the growth of GaN, InGaN, and AlGaN to grow quantum dots. In these studies it has been demostrated that silicon acts as a surfactant at the initial stages of growth, inducing a three-dimensional Stranski-Krastanow growth mode.…”

Section: Discussionmentioning

confidence: 99%

Structural and optical properties of Si-doped GaN

et al. 2000

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Structural and optical properties of Si-doped GaN thin films grown by metal-organic chemical vapor deposition have been studied by means of high resolution x-ray diffraction ͑XRD͒, atomic force microscopy, photoluminescence, photothermal deflection spectroscopy, and optical transmission measurements. The incorporation of silicon in the GaN films leads to pronounced tensile stress. The energy position of the neutral donor bound excitonic emission correlates with the measured stress. The stress induced near band gap luminescence shift is estimated to 19Ϯ2 meV/GPa. An increasing concentration of dopant impurities in the films leads to asymmetries of the XRD and photoluminescence spectra, which are probably related to a stress induced inhomogeneous distribution of dopants. Atomic force microscopy observations of surface modulation with increasing silicon doping support this latter statement. Transmission and photothermal deflection spectroscopy measurements are used to determine the band gap energy and Urbach energy of highly doped samples.

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Section: Discussionmentioning

confidence: 99%

Structural and optical properties of Si-doped GaN

et al. 2000

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“…al. [3], but in this case the growth, that was undertaken by CVD, was not controlled by an intrinsic SK mode, and the size of the dots was rather large (typically 40 nm).…”

Section: Introductionmentioning

confidence: 99%

Evidence of 2D-3D transition during the first stages of GaN growth on AlN

Widmann

Daudin

Feuillet

et al. 1997

MRS Internet j. nitride semicond. res.

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In order to identify the strain relaxation mechanism, Molecular Beam Epitaxy of wurtzite GaN on AlN was monitored in situ using Reflection High Energy Electron Diffraction (RHEED). In the substrate temperature range between 620°C and 720°C, a Stransky-Krastanov (SK) transition was evidenced, resulting in a 2D-3D transition after completion of 2 monolayers, with subsequent coalescence of 3D islands, eventually resulting in a smooth surface. Quantitative analysis of the RHEED pattern allowed us to determine that island formation is associated with elastic relaxation. After island coalescence, a progressive plastic relaxation is observed. The size and density of 3D islands was varied as a function of the growth parameters. AFM experiments revealed that the size of the GaN islands, about 8 nm large and 2 nm high, was small enough to expect quantum effects. It was found that capping of the islands by AlN resulted in a smooth surface after deposition of a few monolayers allowing us to grow a »superlattice» of islands by periodically repeating the process.

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“…Such signatures are routinely analysed to support the identification of excitons and biexcitons in micro-photoluminescence (m-PL) spectroscopy 13,24,25 . However, for the majority of wurtzite c-plane GaN/AlN QDs 26,27 with diameters larger than E6 nm, this picture cannot be valid anymore for the following reasons. The strong internal piezo-and pyroelectric fields separate the electron-from the holesubsystem and cause a very distinct confinement in the growthdirection (c-axis) for both charge carrier types.…”

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confidence: 99%

Manifestation of unconventional biexciton states in quantum dots

et al. 2014

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Although semiconductor excitons consist of a fermionic subsystem (electron and hole), they carry an integer net spin similar to Cooper-electron-pairs. While the latter cause superconductivity by forming a Bose-Einstein-condensate, excitonic condensation is impeded by, for example, a fast radiative decay of the electron-hole pairs. Here, we investigate the behaviour of two electron-hole pairs in a quantum dot with wurtzite crystal structure evoking a charge carrier separation on the basis of large spontaneous and piezoelectric polarizations, thus reducing carrier overlap and consequently decay probabilities. As a direct consequence, we find a hybrid-biexciton complex with a water molecule-like charge distribution enabling anomalous spin configurations. In contrast to the conventional-biexciton complex with a net spin of s ¼ 0, the hybrid-biexciton exhibits s ¼ ± 3, leading to completely different photoluminescence signatures in addition to drastically enhanced charge carrier-binding energies. Consequently, the biexcitonic cascade via the dark exciton can be enhanced on the rise of temperature as approved by photon cross-correlation measurements.

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Self-assembling GaN quantum dots on AlxGa1−xN surfaces using a surfactant

Cited by 281 publications

References 0 publications

Structural and optical properties of Si-doped GaN

Structural and optical properties of Si-doped GaN

Evidence of 2D-3D transition during the first stages of GaN growth on AlN

Manifestation of unconventional biexciton states in quantum dots

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