Ashtekar S, Scott G, Lyding J, Gruebele M. Direct imaging of two-state dynamics on the amorphous silicon surface.
PHYSICAL REVIEW LETTERS 2011;
106:235501. [PMID:
21770518 DOI:
10.1103/physrevlett.106.235501]
[Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2011] [Indexed: 05/31/2023]
Abstract
Amorphous silicon is an important material, amidst a debate whether or not it is a glass. We produce amorphous Si surfaces by ion bombardment and vapor growth, and image discrete Si clusters which hop by two-state dynamics at 295 K. Independent of surface preparation, these clusters have an average diameter of ∼5 atoms. Given prior results for metallic glasses, we suggest that this cluster size is a universal feature. The hopping activation free energy of 0.93±0.15 eV is rather small, in agreement with a previously untested surface glass model. Hydrogenation quenches the two-state dynamics, apparently by increasing surface crystallinity.
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