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arXiv · 2006.01907

Quantification of nanoscale density fluctuations in hydrogenated amorphous silicon

Eike Gericke·Jimmy Melskens·Robert Wendt·Markus Wollgarten·Armin Hoell·Klaus Lips
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Abstract

The nanostructure of hydrogenated amorphous silicon (a Si:H) is studied by a combination of small-angle X-ray (SAXS) and neutron scattering (SANS) with a spatial resolution of 0.8 nm. The a-Si:H materials were deposited using a range of widely varied conditions and are representative for this class of materials. We identify two different phases which are embedded in the a-Si:H matrix and quantified both according to their scattering cross-sections. First, 1.2 nm sized voids (multivacancies with more than 10 missing atoms) which form a superlattice with 1.6 nm void-to-void distance are detected. The voids are found in concentrations as high as 6*10^19 ccm in a-Si:H material that is deposited at a high rate. Second, dense ordered domains (DOD) that are depleted of hydrogen with 1 nm average diameter are found. The DOD tend to form 10-15 nm sized aggregates and are largely found in all a-Si:H materials considered here. These quantitative findings make it possible to understand the complex correlation between structure and electronic properties of a-Si:H and directly link them to the light-induced formation of defects. Finally, a structural model is derived, which verifies theoretical predictions about the nanostructure of a-Si:H.

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Eike Gericke, Jimmy Melskens, Robert Wendt, Markus Wollgarten, Armin Hoell, Klaus Lips. 2020-06-02. Quantification of nanoscale density fluctuations in hydrogenated amorphous silicon. https://doi.org/10.1103/physrevlett.125.185501

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