Monitoring the Formation of Nanowires by Line-of-Sight Quadrupole Mass Spectrometry: A Comprehensive Description of the Temporal Evolution of GaN Nanowire Ensembles

Fernández-Garrido, Sergio; Zettler, Johannes K.; Geelhaar, Lutz; Brandt, O.

doi:10.1021/nl504778s

Cited by 61 publications

(140 citation statements)

References 64 publications

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“…The alignment between the diffraction patterns for AlN and TiN demonstrates that AlN forms epitaxially on TiN. The delay evidences that nucleation of AlN on sputtered TiN is preceded by an incubation time, similar to what is characteristic for GaN NW growth …”

mentioning

confidence: 53%

Self‐Assembly of Well‐Separated AlN Nanowires Directly on Sputtered Metallic TiN Films

Azadmand

Auzelle

Lähnemann

et al. 2020

Physica Rapid Research Ltrs

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Herein, the self‐assembled formation of AlN nanowires (NWs) by molecular beam epitaxy on sputtered TiN films on sapphire is demonstrated. This choice of substrate allows growth at an exceptionally high temperature of 1180 °C. In contrast to previous reports, the NWs are well separated and do not suffer from pronounced coalescence. This achievement is explained by sufficient Al adatom diffusion on the substrate and the NW sidewalls. The high crystalline quality of the NWs is evidenced by the observation of near‐band‐edge emission in the cathodoluminescence spectrum. The key factor for the low NW coalescence is the TiN film, which spectroscopic ellipsometry and Raman spectroscopy indicate to be stoichiometric. Its metallic nature will be beneficial for optoelectronic devices using these NWs as the basis for (Al,Ga)N/AlN heterostructures emitting in the deep ultraviolet spectral range.

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confidence: 53%

Self‐Assembly of Well‐Separated AlN Nanowires Directly on Sputtered Metallic TiN Films

Azadmand

Auzelle

Lähnemann

et al. 2020

Physica Rapid Research Ltrs

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“…Therefore, the elongation rate is not yet limited by thermal decomposition. 3,18 We stress that, despite the large III/V flux ratios used (up to 2.3), the growth still takes place under an excess of N because of the high desorption rate of Ga adatoms. Otherwise, a compact layer would form because of NW radial growth.…”

Section: ■ Results and Discussionmentioning

confidence: 95%

High-Temperature Growth of GaN Nanowires by Molecular Beam Epitaxy: Toward the Material Quality of Bulk GaN

Zettler

Hauswald

Corfdir

et al. 2015

Crystal Growth & Design

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In molecular beam epitaxy, the spontaneous formation of GaN nanowires on Si(111) substrates at elevated temperatures is limited by the long incubation time that precedes nanowire nucleation. In this work, we present three growth approaches to minimize the incubation time and to thus facilitate significantly higher growth temperatures (up to 875°C). We achieve this advancement by (i) using III/V flux ratios of >1 to compensate for Ga desorption, (ii) introducing a two-step growth procedure, and (iii) using an AlN buffer layer to favor GaN nucleation. The GaN nanowire ensembles grown at so far unexplored substrate temperatures exhibit excitonic transitions with sub-meV linewidths comparable to those of state-of-the-art free-standing GaN layers grown by hydride vapor phase epitaxy.

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“…In contrast to previous decomposition studies, 25,26 we monitor the decomposition in situ by QMS [29][30][31] and can thus control this process. Since the dissociation of GaN in UHV is thermally activated, 32-34 the decomposition rate of GaN nanowires is controlled primarily by the substrate temperature.…”

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Observation of Dielectrically Confined Excitons in Ultrathin GaN Nanowires up to Room Temperature

et al. 2016

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The realization of semiconductor structures with stable excitons at room temperature is crucial for the development of excitonics and polaritonics. Quantum confinement has commonly been employed for enhancing excitonic effects in semiconductor heterostructures. Dielectric confinement, which gives rises to much stronger enhancement, has proven to be more difficult to achieve because of the rapid nonradiative surface/interface recombination in hybrid dielectric-semiconductor structures. Here, we demonstrate intense excitonic emission from bare GaN nanowires with diameters down to 6 nm. The large dielectric mismatch between the nanowires and vacuum greatly enhances the Coulomb interaction, with the thinnest nanowires showing the strongest dielectric confinement and the highest radiative efficiency at room temperature. In situ monitoring of the fabrication of these structures allows one to accurately control the degree of dielectric enhancement. These ultrathin nanowires may constitute the basis for the fabrication of advanced low-dimensional structures with an unprecedented degree of confinement.

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Monitoring the Formation of Nanowires by Line-of-Sight Quadrupole Mass Spectrometry: A Comprehensive Description of the Temporal Evolution of GaN Nanowire Ensembles

Cited by 61 publications

References 64 publications

Self‐Assembly of Well‐Separated AlN Nanowires Directly on Sputtered Metallic TiN Films

Self‐Assembly of Well‐Separated AlN Nanowires Directly on Sputtered Metallic TiN Films

High-Temperature Growth of GaN Nanowires by Molecular Beam Epitaxy: Toward the Material Quality of Bulk GaN

Observation of Dielectrically Confined Excitons in Ultrathin GaN Nanowires up to Room Temperature

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