Volume 112, Number 2, October 2015
|Number of page(s)||6|
|Section||Condensed Matter: Structural, Mechanical and Thermal Properties|
|Published online||05 November 2015|
Light-induced metastability in pure and hydrogenated amorphous silicon
1 Department of Physics, University of California - Berkeley, CA 94720, USA
2 Naval Research Laboratory - Washington D.C., 20375, USA
3 Department of Materials Science and Engineering, University of California - Berkeley, CA 94720, USA
4 National Renewable Energy Laboratory - Golden, CO 80401, USA
Received: 12 July 2015
Accepted: 16 October 2015
Light soaking is found to increase the specific heat C and internal friction of pure (a-Si) and hydrogenated (a-Si:H) amorphous silicon. At the lowest temperatures, the increases in C and are consistent with an increased density of two-level systems (TLS). The light-induced increase in C persists to room temperature. Neither the sound velocity nor shear modulus change with light soaking indicating that the Debye specific heat is unchanged which suggests that light soaking creates localized vibrational modes in addition to TLS. The increase can be reversibly added and removed by light soaking and annealing, respectively, suggesting that it is related to the Staebler-Wronski effect (SWE), even in a-Si without H, and involves a reversible nanoscale structural rearrangement that is facilitated by, but does not require, H to occur.
PACS: 61.43.Dq – Amorphous semiconductors, metals, and alloys / 65.60.+a – Thermal properties of amorphous solids and glasses: heat capacity, thermal expansion, etc. / 62.40.+i – Anelasticity, internal friction, stress relaxation, and mechanical resonances
© EPLA, 2015
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