Light absorption in Ge nanoclusters embedded in SiO2: comparison between magnetron sputtering and sol–gel synthesis

Cosentino, Salvatore; Knebel, S.; Mirabella, S.; Gibilisco, S.; Simone, F.; Bracht, H.; Wilde, Gerhard; Terrasi, A.

doi:10.1007/s00339-013-8101-9

Cited by 4 publications

(7 citation statements)

References 39 publications

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“…The mean diameter of the Ge nanocrystals increases usually with the temperature and duration of the annealing process. This is observed for all deposition techniques like MS, ion‐implantation, and CVD . In addition, the crystallization process starts at lower temperatures for longer annealing times …”

Section: Synthesis Of Ge Nanocrystals Via Phase Separation From Supermentioning

confidence: 66%

“…At this temperature, however, crystalline and amorphous portions can be found . Only after annealing at 800 °C, the Ge is fully crystalline . The crystallization temperature of the SiO 2 is much higher than the one of Ge.…”

Section: Influence Of Different Matrix Materialsmentioning

confidence: 91%

“…The classic furnace tube uses heating filaments. The temperature ramps are comparatively low and the annealing time is usually in the range of 15 min to 1 h . Compared to classic furnace tools, RTP tools feature lower energy costs and earlier crystallization processes .…”

Section: Synthesis Of Ge Nanocrystals Via Phase Separation From Supermentioning

confidence: 99%

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A Review on Ge Nanocrystals Embedded in SiO₂ and High‐k Dielectrics

Lehninger

Beyer

Heitmann

2018

Physica Status Solidi (a)

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In this article, the work on Ge nanocrystals embedded in dielectric films formed by phase separation from supersaturated solid solutions is reviewed. Different methods to synthesize supersaturated solid solutions are covered, e.g., magnetron sputtering, ion implantation, and chemical vapor deposition. The phase separation is activated by subsequent high temperature annealing. Important parameters that influence the formation and properties of the Ge nanocrystals are discussed. Various matrix materials like SiO2, Al2O3, HfO2, HfAlOx, Lu2O3, ZrO2, TaZrOx, and Si3N4 are reported in the literature. The influence of the matrix on the formation and properties of the Ge nanocrystals is addressed in this review. Ge nanocrystals are investigated for applications such as charge storage nodes in nonvolatile memory devices or as silicon technology compatible light emitters. A key to establish these applications seems to be embedding the Ge nanocrystals in still amorphous matrices. This could help to avoid grain boundaries that act as leakage paths for electrical charges (unfavorable for nonvolatile memories) and facilitate defects, which could act as recombination centers (unfavorable for light emitters). A further important point is the synthesis of size and position controlled Ge nanocrystals. Both aspects are reviewed for Ge nanocrystals embedded in the mentioned matrix materials.

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Section: Synthesis Of Ge Nanocrystals Via Phase Separation From Supermentioning

confidence: 66%

Section: Influence Of Different Matrix Materialsmentioning

confidence: 91%

See 1 more Smart Citation

A Review on Ge Nanocrystals Embedded in SiO₂ and High‐k Dielectrics

Lehninger

Beyer

Heitmann

2018

Physica Status Solidi (a)

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“…[26][27][28] Nevertheless, there are clear discrepancies in the theoretical modeling and experimental results concerning germanium NCs, and therefore, no well-established generally accepted relationship between germanium NC size and optical bandgap exists. [26][27][28][29][30] In particular Takeoka et al 23 reports that a PL energy of 1.25 eV corresponds to a relatively small NC diameter of ,2 nm, whereas Niquet et al 28 reports the formation of much larger germanium NCs with diameters of ,8 nm upon annealing at the same temperature. However, it is unclear whether the amount of excess germanium and/or sputtering conditions were similar in these two studies.…”

Section: Resultsmentioning

confidence: 99%

Carrier multiplication in germanium nanocrystals

et al. 2015

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Carrier multiplication is demonstrated in a solid-state dispersion of germanium nanocrystals in a silicon-dioxide matrix. This is performed by comparing ultrafast photo-induced absorption transients at different pump photon energies below and above the threshold energy for this process. The average germanium nanocrystal size is approximately 5-6 nm, as inferred from photoluminescence and Raman spectra. A carrier multiplication efficiency of approximately 190% is measured for photo-excitation at 2.8 times the optical bandgap of germanium nanocrystals, deduced from their photoluminescence spectra.

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“…Details on the SiGeO deposition, Ge diffusion, QD growth and structural order of Ge QDs are given in ref. 4,25,33. The presence and the size distribution of Ge QDs were evaluated by cross sectional transmission electron microscopy in scanning mode (STEM) analysis.…”

Section: Methodsmentioning

confidence: 99%

The role of the interface in germanium quantum dots: when not only size matters for quantum confinement effects

et al. 2015

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Quantum confinement (QC) typically assumes a sharp interface between a nanostructure and its environment, leading to an abrupt change in the potential for confined electrons and holes. When the interface is not ideally sharp and clean, significant deviations from the QC rule appear and other parameters beyond the nanostructure size play a considerable role. In this work we elucidate the role of the interface on QC in Ge quantum dots (QDs) synthesized by rf-magnetron sputtering or plasma enhanced chemical vapor deposition (PECVD). Through a detailed electron energy loss spectroscopy (EELS) analysis we investigated the structural and chemical properties of QD interfaces. PECVD QDs exhibit a sharper interface compared to sputter ones, which also evidences a larger contribution of mixed Ge-oxide states. Such a difference strongly modifies the QC strength, as experimentally verified by light absorption spectroscopy. A large size-tuning of the optical bandgap and an increase in the oscillator strength occur when the interface is sharp. A spatially dependent effective mass (SPDEM) model is employed to account for the interface difference between Ge QDs, pointing out a larger reduction in the exciton effective mass in the sharper interface case. These results add new insights into the role of interfaces on confined systems, and open the route for reliable exploitation of QC effects.

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Light absorption in Ge nanoclusters embedded in SiO2: comparison between magnetron sputtering and sol–gel synthesis

Cited by 4 publications

References 39 publications

A Review on Ge Nanocrystals Embedded in SiO₂ and High‐k Dielectrics

A Review on Ge Nanocrystals Embedded in SiO₂ and High‐k Dielectrics

Carrier multiplication in germanium nanocrystals

The role of the interface in germanium quantum dots: when not only size matters for quantum confinement effects

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Light absorption in Ge nanoclusters embedded in SiO2: comparison between magnetron sputtering and sol–gel synthesis

Cited by 4 publications

References 39 publications

A Review on Ge Nanocrystals Embedded in SiO2 and High‐k Dielectrics

A Review on Ge Nanocrystals Embedded in SiO2 and High‐k Dielectrics

Carrier multiplication in germanium nanocrystals

The role of the interface in germanium quantum dots: when not only size matters for quantum confinement effects

Contact Info

Product

Resources

About

A Review on Ge Nanocrystals Embedded in SiO₂ and High‐k Dielectrics

A Review on Ge Nanocrystals Embedded in SiO₂ and High‐k Dielectrics