Hydrogen-free amorphous silicon with no tunneling states.
- Author(s): Liu, Xiao
- Queen, Daniel R
- Metcalf, Thomas H
- Karel, Julie E
- Hellman, Frances
- et al.
Published Web Locationhttps://doi.org/10.1103/physrevlett.113.025503
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.