title: Hydrogen-free amorphous silicon with no tunneling states.
abstract: 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.
authors: Naval Research Laboratory, Code 7130, Washington, D.C. 20375, USA.
authors: Xiao
authors: X
authors: Liu
authors: NRC Postdoctoral Associate, Naval Research Laboratory, Washington, D.C. 20375, USA.
authors: Daniel R
authors: DR
authors: Queen
authors: Naval Research Laboratory, Code 7130, Washington, D.C. 20375, USA.
authors: Thomas H
authors: TH
authors: Metcalf
authors: Department of Physics, University of California, Berkeley, Berkeley, California 94720, USA.
authors: Julie E
authors: JE
authors: Karel
authors: Department of Physics, University of California, Berkeley, Berkeley, California 94720, USA and Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, California 94720, USA.
authors: Frances
authors: F
authors: Hellman