Low temperature internal friction study of light-induced structural instability in hydrogenated amorphous silicon

Liu, Xiao; Spiel, C.L; Pohl, Robert Wichard; Iwaniczko, E.; Crandall, Richard S.

doi:10.1016/s0022-3093(00)00050-8

Cited by 9 publications

(5 citation statements)

References 15 publications

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“…ΔQ −1 /Q −1 for the 45 • C and 200 • C a-Si films is 5% and 3%, respectively, whereas Δn 0 /n 0 is 200% and 70% and Δc ex /c ex is 56% and 53%, respectively. For the a-Si:H film, the magnitudes of both Q −1 and ΔQ −1 ≤ 10 −5 are similarly smaller than expected given the large values of C and ΔC but are comparable to previous results [8]. Thus the low-energy excitations seen in C are more sensitive to light soaking than those seen in…”

supporting

confidence: 83%

“…However, we have recently shown that the same reduction of TLS seen in a-Si:H can be achieved in hydrogen-free a-Si by depositing the films at moderately elevated growth temperature [13][14][15][16][17]. The light-induced increase in both the TLS and DBs in a-Si:H suggests that both phenomena are related [8]. Exploring the relationship between light soaking and TLS may therefore elucidate the underlying structural origin of each.…”

mentioning

confidence: 90%

“…In addition to generating DBs, light soaking also increases the low-temperature acoustic loss in a-Si:H [8] which is caused by low-energy excitations described by the two-level systems (TLS) model [9,10]. TLS dominate the low-temperature acoustic, dielectric, and thermal properties of amorphous solids [11,12].…”

mentioning

confidence: 99%

“…After initial C, Q −1 , and v l measurements, films were light soaked using a PV Measurements Inc. small area AM1.5G solar simulator for 7 days which was sufficient to saturate the DB density (n DB ) [8,31]. For the specific heat samples, films were exposed through the 50 nm nitride membrane which was measured to be 60% transmissive.…”

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confidence: 99%

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Light-induced metastability in pure and hydrogenated amorphous silicon

Queen

Liu

Karel

et al. 2015

EPL

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Light soaking is found to increase the specific heat C and internal friction Q −1 of pure (a-Si) and hydrogenated (a-Si:H) amorphous silicon. At the lowest temperatures, the increases in C and Q −1 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.

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supporting

confidence: 83%

mentioning

confidence: 90%

mentioning

confidence: 99%

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confidence: 99%

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Light-induced metastability in pure and hydrogenated amorphous silicon

Queen

Liu

Karel

et al. 2015

EPL

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“…Recently it is reported for a-Si:H that the internal friction observed between 80 K and 400 K disappeared after the thermal desorption treatment to eliminate TDH 650K alone, indicating that the internal friction is associated with the motion of hydrogen molecule (H 2 ) in microvoids [6]. Light-soaking experiments at low temperatures reported an increase in the internal friction below about 300 K after light-soaking and its recovery after annealing at 423 K [6,7], indicating that the light-soaking induces the recoverable structural relaxation. Very recently, it is reported that the light-induced hydrogen evolution (LIHE) from a-Si:H takes place when the light-soaking is made above room temperature in a vacuum [8,9].…”

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confidence: 99%

Mechanical Spectroscopy Study on the Light Soaking Effect on Hydrogenated Amorphous Silicon

Mizubayashi

Sakata

Tanimoto

2012

SSP

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For hydrogenated amorphous silicon (a-Si:H) films deposited at temperatures between 423 K and 623 K (a-Si:H423Kand so on), the light-induced changes in the internal friction between 80 K and 400 K were studied. The internal friction is associated with H2motion in microvoid networks, and shows the mild temperature dependence between about 80 K and 300 K (Q-180-300K) and the almost linear increase above 300 K (Q-1>300K). BothQ-180-300KandQ-1>300Kdecrease with increasing the deposition temperature, and show the mild temperature dependence ina-Si:H623K. The white light soaking with 100 mW/cm2(WLS100and so on) below 300 K caused a change inQ-180-300Kand no changes inQ-1>300K, respectively, and the light-induced changes inQ-180-300Krecovered after annealing at 423 K. The wide distribution of activation energies for H2motions between microvoids indicate that most of neighboring microvoids are connected through windows, i.e., the microvoid networks are existing ina-Si:H, and the spatially loose or solid structures are responsible for the low or high activation energies for the H2motion between microvoids, respectively. Furthermore, the light-induced hydrogen evolution (LIHE) was observed for WLS200to WLS400in a vacuum between 400 and 500 K, resulting in the disappearance of the internal friction due to the H2motion in the microvoid network.

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