Hydrogen-free amorphous silicon with no tunneling states

Xiao Liu, Daniel R. Queen, Thomas H. Metcalf, Julie E. Karel, Frances Hellman

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61 Citations (Scopus)


The ubiquitous low-energy excitations, known as two-level tunneling systems (TLSs), are one of the universal phenomena of amorphous solids. Low temperature elastic measurements show that e-beam amorphous silicon (a-Si) contains a variable density of TLSs which diminishes as the growth temperature reaches 400°C. Structural analyses show that these a-Si films become denser and more structurally ordered. We conclude that the enhanced surface energetics at a high growth temperature improved the amorphous structural network of e-beam a-Si and removed TLSs. This work obviates the role hydrogen was previously thought to play in removing TLSs in the hydrogenated form of a-Si and suggests it is possible to prepare perfect amorphous solids with crystal-like properties for applications.

Original languageEnglish
Article number025503
Number of pages5
JournalPhysical Review Letters
Issue number2
Publication statusPublished - 8 Jul 2014
Externally publishedYes

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