Similarities in the kinetics of photocrystallization and photodarkening in a-Se

Tallman, R. E.; Reznik, A.; Weinstein, B. A.; Baranovskiǐ, S. D.; Rowlands, J. A.

doi:10.1063/1.3026173

Cited by 11 publications

(6 citation statements)

References 23 publications

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“…Using a double-well energy configuration, it was shown that the energy barrier between the ground state and a metastable state in pure a-Se was 0.8 eV [2]. A similar activation behavior was observed in photo-induced crystallization (PC) of a-Se studied by Raman spectroscopy [3]. This similarity suggests that the formation kinetics of PD and PC are controlled by the same configurational changes occurring via photo-induced metastable defects.…”

Section: Introductionmentioning

confidence: 61%

The effect of the substrate on transient photodarkening in stabilized amorphous selenium

Abbaszadeh

Rom

Bubon

et al. 2012

Journal of Non-Crystalline Solids

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Section: Introductionmentioning

confidence: 61%

The effect of the substrate on transient photodarkening in stabilized amorphous selenium

Abbaszadeh

Rom

Bubon

et al. 2012

Journal of Non-Crystalline Solids

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“…Illuminated Se samples were found to be partially crystallized, which may present the photo-enhanced crystallization, being known for Se for a long time [15,16]. However, no appreciable anisotropic structures were detected.…”

Section: Resultsmentioning

confidence: 84%

Photoinduced vector deformations of semi‐freely fixed glassy As‐S(Se)

Tanaka

Mikami

2011

Phys. Status Solidi C

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The chalcogenide glass is known to exhibit a variety of vector photo‐deformations. The present work studies the deformation in glassy As‐S(Se) films and flakes, which are laid on viscous grease layers. Upon bandgap illumination of linearly polarized cw laser light, the film and flake exhibit anisotropic wrinkles and extensions, respectively, while the directions change with the composition. As2S(Se)3 samples deform in the direction orthogonal to the electric field of the light, but pure Se deforms in parallel to the electric field. And, in the As‐Se system, an orthogonal‐parallel directional change appears at the As content of ∼1 at.%. X‐ray diffraction and Raman‐scattering spectroscopy detect no anisotropic atomic changes. The orthogonal deformation has been ascribed to optical pressure, while the parallel in Se may be triggered by polariton‐plasmon waves. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…Therefore, we suggest that experimentally observed crystallization of the a-Se samples under subband-gap illumination [7,30] should be linked to the double-electron excitation process.…”

Section: Photoinduced Lattice Relaxationmentioning

confidence: 92%

“…The direct evidence of the valence alteration in a-Se is experimentally detected unpaired electrons which appear under light illumination [2]. It is believed that the VAP defects are responsible for many of the photoinduced effects including photodarkening (PD) [6][7][8], photoinduced crystallization [7] and volume expansion [9][10][11] as they induce the subband gap defect states [12][13][14][15] . Although a link between these effects is not confirmed with direct experiments, they all have similar kinetics and are shown to be thermally activated processes with similar activation energies around ∼0.9 eV [6,7] -the value which was suggested for the VAP defect relaxation [16].…”

Section: Introductionmentioning

confidence: 99%

Two-Step Photoexcitation Mechanism in Amorphous Se

2014

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The first-principles simulations are applied to study a photoinduced metastability in amorphous selenium and contribution of the valence-alteration pair (VAP) defects in this process. The VAP defect is confirmed to be the equilibrium defect; it minimizes the destabilizing interaction induced by disorientation of the lone-pair (LP) electrons along the Se chains, and, thus, relieves tension in a system. The photoexcitation involves the LP electrons, and it is proposed to be described by two coexisting processes, namely, single-and double-electron excitations. Both processes are found to induce the defect states in the band gap and cause experimentally observed photodarkening; however, only double-electron excitation is capable of triggering bond rearrangement and structural transformation. Lattice relaxation, which follows bond rearrangement, occurs with characteristic energy of −0.9 AE 0.3 eV. It is found to promote formation of energetically favorable VAP defects and to trigger the ringlike to helixlike transformations, thus, ultimately stimulating the photoinduced crystallization. The photoinduced crystallization is directly simulated in a system characterized by increased crystalline order.

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Similarities in the kinetics of photocrystallization and photodarkening in a-Se

Cited by 11 publications

References 23 publications

The effect of the substrate on transient photodarkening in stabilized amorphous selenium

The effect of the substrate on transient photodarkening in stabilized amorphous selenium

Photoinduced vector deformations of semi‐freely fixed glassy As‐S(Se)

Two-Step Photoexcitation Mechanism in Amorphous Se

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