Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International



Home > Press > Order in the disorder: density fluctuations in amorphous silicon discovered

Structural model of highly porous a-Si:H, which was deposited very quickly, calculated based on measurement data. Densely ordered domains (DOD) are drawn in blue and cavities in red. The grey layer represents the disordered a-Si:H matrix. The round sections show the nanostructures enlarged to atomic resolution (below, Si atoms: grey, Si atoms on the surfaces of the voids: red; H: white)

CREDIT
Eike Gericke/HZB
Structural model of highly porous a-Si:H, which was deposited very quickly, calculated based on measurement data. Densely ordered domains (DOD) are drawn in blue and cavities in red. The grey layer represents the disordered a-Si:H matrix. The round sections show the nanostructures enlarged to atomic resolution (below, Si atoms: grey, Si atoms on the surfaces of the voids: red; H: white) CREDIT Eike Gericke/HZB

Abstract:
Silicon does not have to be crystalline, but can also be produced as an amorphous thin film. In such amorphous films, the atomic structure is disordered like in a liquid or glass. If additional hydrogen is incorporated during the production of these thin layers, so-called a-Si:H layers are formed. "Such a-Si:H thin films have been known for decades and are used for various applications, for example as contact layers in world record tandem solar cells made of perovskite and silicon, recently developed by HZB" explains Prof. Klaus Lips from HZB. "With this study, we show that the a-Si:H is by no means a homogeneously amorphous material. The amorphous matrix is interspersed with nanometre-sized areas of varying local density, from cavities to areas of extremely high order," the physicist comments.

Order in the disorder: density fluctuations in amorphous silicon discovered

Berlin, Germany | Posted on October 30th, 2020

In cooperation with the Technical Universities of Eindhoven and Delft, Lips and his team have succeeded for the first time in experimentally observing and quantitatively measuring these inhomogeneities in differently produced a-Si:H thin films. To do this, they combined the results of complementary analytical methods to form an overall picture.

"We find a nanoscopic order in the disorder of the a-Si:H layers by x-ray scattering measurements performed at BESSY II. We were then able to determine the distribution of the hydrogen atoms in the amorphous network by neutron scattering at the former research reactor BER II at the HZB site Wannsee", says Eike Gericke, PhD student and first author of the paper. Further insights were provided by the electron microscopy performed at the CCMS Corelab and measurements of electron spin resonance (ESR).

"We were able to discover nanometer-sized voids, which are created by slightly more than 10 missing atoms. These voids arrange themselves into clusters with a recurrent distance of about 1.6 nanometres to each other," explains Gericke. These voids are found in increased concentrations when the a-Si:H layer has been deposited at a very high rate.

The researchers also found nanometre-sized regions with higher order compared to the surrounding disordered material. These densely ordered domains (DOD) contain hardly any hydrogen. "The DODs form aggregates of up to 15 nanometres in diameter and are found in all the a-Si:H materials considered here," explains Gericke.

"The DOD regions have been theoretically predicted in 2012 and are able to reduce mechanical stress in the material and thus contribute to the stability of the a-Si:H thin film. The voids on the other hand, can promote electronic degradation of the semiconductor layers as indicated by ESR measurements," says Klaus Lips.

Targeted optimization of manufacturing processes with regard to the substructures now discovered could enable new applications such as optical waveguides for programmable photonic systems or a future silicon battery technology. Last but not least, the findings will also help to finally unravel the microscopic mechanism of light-induced degradation of a-Si:H solar cells, one of the puzzles the scientific community is trying to solve since more than 40 years.

####

For more information, please click here

Contacts:
Antonia Roetger


@HZBde

Copyright © Helmholtz-Zentrum Berlin für Materialien und Energie

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

RELATED JOURNAL ARTICLE:

Related News Press

Possible Futures

Researchers unveil mystery inside Li- o2 batteries September 30th, 2022

Synthesis of air-stable room-temperature van der Waals magnetic thin flakes September 30th, 2022

Layer Hall effect and hidden Berry curvature in antiferromagnetic insulators September 30th, 2022

ACM Research Launches New Furnace Tool for Thermal Atomic Layer Deposition to Support Advanced Semiconductor Manufacturing Requirements: Ultra Fn A Furnace Tool Shipped to China-Based Foundry Customer September 30th, 2022

Optical computing/Photonic computing

Conformal optical black hole for cavity September 30th, 2022

“Twisty” photons could turbocharge next-gen quantum communication: Team’s on-chip technology uses orbital angular momentum to encode more information into a single photon September 23rd, 2022

Purdue researchers suggest novel way to generate a light source made from entangled photons: This research shows promise in establishing the measurement of entangled photons down to the attosecond, and possibly even zeptosecond September 9th, 2022

Chiral quasi bound states in the continuum for high-purity circularly polarized light source: Researchers demonstrate high-purity, highly directional, and high-Q circularly polarized light source from spontaneous emission to laser September 9th, 2022

Discoveries

Surface microstructures of lunar soil returned by Chang’e-5 mission reveal an intermediate stage in space weathering process September 30th, 2022

Researchers unveil mystery inside Li- o2 batteries September 30th, 2022

Synthesis of air-stable room-temperature van der Waals magnetic thin flakes September 30th, 2022

Layer Hall effect and hidden Berry curvature in antiferromagnetic insulators September 30th, 2022

Announcements

Researchers unveil mystery inside Li- o2 batteries September 30th, 2022

Synthesis of air-stable room-temperature van der Waals magnetic thin flakes September 30th, 2022

Layer Hall effect and hidden Berry curvature in antiferromagnetic insulators September 30th, 2022

ACM Research Launches New Furnace Tool for Thermal Atomic Layer Deposition to Support Advanced Semiconductor Manufacturing Requirements: Ultra Fn A Furnace Tool Shipped to China-Based Foundry Customer September 30th, 2022

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers/Posters

Conformal optical black hole for cavity September 30th, 2022

Cleveland researchers reveal new strategy to prevent blood clots without increasing the risk of bleeding: University Hospitals and Case Western Reserve University findings may be especially impactful for cancer patients who experience blood clot complications September 30th, 2022

Ultrasmall VN/Co heterostructure with optimized N active sites anchored in N-doped graphitic nanocarbons for boosting hydrogen evolution September 30th, 2022

Layer Hall effect and hidden Berry curvature in antiferromagnetic insulators September 30th, 2022

Battery Technology/Capacitors/Generators/Piezoelectrics/Thermoelectrics/Energy storage

Conformal optical black hole for cavity September 30th, 2022

Researchers unveil mystery inside Li- o2 batteries September 30th, 2022

Modulating MoSe2 functional plane via doping-defect engineering strategy to develop conductive and electrocatalytic mediators in Li-S batteries September 23rd, 2022

Heat-resistant nanophotonic material could help turn heat into electricity: The key to beating the heat is degrading the materials in advance September 23rd, 2022

Photonics/Optics/Lasers

“Twisty” photons could turbocharge next-gen quantum communication: Team’s on-chip technology uses orbital angular momentum to encode more information into a single photon September 23rd, 2022

Purdue researchers suggest novel way to generate a light source made from entangled photons: This research shows promise in establishing the measurement of entangled photons down to the attosecond, and possibly even zeptosecond September 9th, 2022

Chiral quasi bound states in the continuum for high-purity circularly polarized light source: Researchers demonstrate high-purity, highly directional, and high-Q circularly polarized light source from spontaneous emission to laser September 9th, 2022

New road towards spin-polarised currents September 9th, 2022

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project