Observing the morphology of single-layered embedded silicon nanocrystals by using temperature-stable TEM membranes

Gutsch, Sebastian; Hiller, Daniel; Laube, J.; Zacharias, Margit; Kübel, Christian

doi:10.3762/bjnano.6.99

Cited by 29 publications

(25 citation statements)

References 49 publications

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“…On the other hand, Perego et al used the results of a SIMS‐XPS study to suggest that P atoms were incorporated into Si NCs of on average ∼2 nm . However, in a NC ensemble grown by self‐organization from SiO‐layers a log‐normal size‐distribution exists that covers also NCs significantly larger than the mean size . Hence, the results presented in that study cannot discriminate between different NC sizes within an ensemble.…”

Section: Introductionmentioning

confidence: 90%

Atom probe tomography of size‐controlled phosphorus doped silicon nanocrystals

Nomoto

Hiller

Gutsch

et al. 2016

Physica Rapid Research Ltrs

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Doping of silicon nanocrystals is essential to control their electronic and optical properties. The incorporation of an impurity into a silicon nanovolume is a nontrivial task due to the self‐purification effect. Here, a systematic atom probe tomography study of the phosphorus distribution and incorporation in size‐controlled silicon nanocrystals embedded in silicon dioxide is presented. Qualitatively, it turns out that the phosphorus distribution in the system follows a universal, nanocrystal‐size independent trend: phosphorus‐enrichment at the interface with a substantial phosphorus‐incorporation in the silicon nanocrystal as small as 2 nm in diameter. This clearly contradicts strict self‐purification. These observations are explained by the bulk‐solubility and ‐segregation behaviour, kinetic effects related to the diffusion lengths, and nanoscale interface strain. The quantitative determination of the amount of phosphorus atoms per quantum dot enables a systematic understanding of phosphorus‐induced effects on optical and electronic properties of silicon nanovolumes.

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Section: Introductionmentioning

confidence: 90%

Atom probe tomography of size‐controlled phosphorus doped silicon nanocrystals

Nomoto

Hiller

Gutsch

et al. 2016

Physica Rapid Research Ltrs

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“…The number of projections was intentionally limited to 36 (in contrast to typically used 2 step widths) to minimize the total electron irradiation dose below the threshold where SiO 2 becomes unstable and Si NCs are formed by the electron beam that were not present before. [6] Due to the limited tilt range objects appear elongated along the z-direction in the tomographic reconstruction, that is, the beam direction in the 0 projection image. The elongation factor can be estimated from the tilt range [21] and is %1.3 for the conditions specified above.…”

Section: Methodsmentioning

confidence: 99%

“…The SiO x /SiO 2 superlattice approach [5] meets these requirements. [6,7] Furthermore, an almost defect-free Si/ SiO 2 interface quality can be achieved by H 2 passivation [8] which in turn results in high luminescence quantum yields (QY) of %25% at room temperature. [9] Very large luminescence quantum yields were also achieved for Si QDs from gas phase synthesis [10] and a hydrogen silsesquioxane based synthesis.…”

Section: Introductionmentioning

confidence: 99%

Determination of Shape and Sphericity of Silicon Quantum Dots Imaged by EFTEM‐Tomography

Hiller

Gutsch

López-Vidrier

et al. 2017

physica status solidi c

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The shape of size‐controlled silicon nanocrystals (Si NCs) embedded in SiO2 is investigated by tomographic energy‐filtered transmission electron microscopy (EFTEM). The sphericity of the quantum dots is determined by computational analyses. In contrast to other fabrication methods, we demonstrate that the NCs in superlattices are non‐agglomerated, individual clusters with slightly oblate spheroidal shape. This allows for low surface‐to‐volume ratios and thereby low non‐radiative defect densities as required by optoelectronic or sensing applications. A near‐spherical shape is also a prerequisite for the direct comparison of Si quantum dots (QDs) with theoretical simulations.

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“…Regarding the downscaling process, high mobility, good process compatibility with the well-developed CMOS technology, and the extension of the photosensitivity range to the near-infrared (NIR) are the properties that make devices based on Ge nanoparticles (Ge-nps) promising candidates to substitute or to improve the conventional Si-based devices [1–7]. However, due to the lower binding energy of Ge atoms in comparison to Si atoms, Ge-nps can be formed in samples annealed at significantly lower synthesis temperatures of 600–900 °C compared to around 1100 °C for Si [8–9]. …”

Section: Introductionmentioning

confidence: 99%

Nanostructured germanium deposited on heated substrates with enhanced photoelectric properties

Stavarache

Maraloiu

Prepelita

et al. 2016

Beilstein J. Nanotechnol.

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SummaryObtaining high-quality materials, based on nanocrystals, at low temperatures is one of the current challenges for opening new paths in improving and developing functional devices in nanoscale electronics and optoelectronics. Here we report a detailed investigation of the optimization of parameters for the in situ synthesis of thin films with high Ge content (50 %) into SiO2. Crystalline Ge nanoparticles were directly formed during co-deposition of SiO2 and Ge on substrates at 300, 400 and 500 °C. Using this approach, effects related to Ge–Ge spacing are emphasized through a significant improvement of the spatial distribution of the Ge nanoparticles and by avoiding multi-step fabrication processes or Ge loss. The influence of the preparation conditions on structural, electrical and optical properties of the fabricated nanostructures was studied by X-ray diffraction, transmission electron microscopy, electrical measurements in dark or under illumination and response time investigations. Finally, we demonstrate the feasibility of the procedure by the means of an Al/n-Si/Ge:SiO2/ITO photodetector test structure. The structures, investigated at room temperature, show superior performance, high photoresponse gain, high responsivity (about 7 AW−1), fast response time (0.5 µs at 4 kHz) and great optoelectronic conversion efficiency of 900% in a wide operation bandwidth, from 450 to 1300 nm. The obtained photoresponse gain and the spectral width are attributed mainly to the high Ge content packed into a SiO2 matrix showing the direct connection between synthesis and optical properties of the tested nanostructures. Our deposition approach put in evidence the great potential of Ge nanoparticles embedded in a SiO2 matrix for hybrid integration, as they may be employed in structures and devices individually or with other materials, hence the possibility of fabricating various heterojunctions on Si, glass or flexible substrates for future development of Si-based integrated optoelectronics.

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Observing the morphology of single-layered embedded silicon nanocrystals by using temperature-stable TEM membranes

Cited by 29 publications

References 49 publications

Atom probe tomography of size‐controlled phosphorus doped silicon nanocrystals

Atom probe tomography of size‐controlled phosphorus doped silicon nanocrystals

Determination of Shape and Sphericity of Silicon Quantum Dots Imaged by EFTEM‐Tomography

Nanostructured germanium deposited on heated substrates with enhanced photoelectric properties

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