Photoinduced effects and metastability in amorphous semiconductors and insulators

Shimakawa, K.; Kolobov, Alexander V.; Elliott, S. R.

doi:10.1080/00018739500101576

Cited by 594 publications

(352 citation statements)

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“…Bandgap light is effective in producing the redshift, 1,5 while subbandgap light can also induce some changes. 1,2,6 The photodarkening phenomenon is demonstrated to arise from photoinduced enhancement of randomness in amorphous structures, 7 while the entity of atomic change is still speculative. 1,2 Chalcogenide glasses also exhibit volume changes upon light illumination.…”

Section: Introductionmentioning

confidence: 99%

“…4 Among a variety of phenomena, reversible photodarkening is one of the most extensively studied. 1,2,5 When a chalcogenide glass, which may be elemental or compound, is exposed to light, it shows a redshift of the optical-absorption edge, which can be recovered with annealing at the glasstransition temperature. Bandgap light is effective in producing the redshift, 1,5 while subbandgap light can also induce some changes.…”

Section: Introductionmentioning

confidence: 99%

“…1,2,5 When a chalcogenide glass, which may be elemental or compound, is exposed to light, it shows a redshift of the optical-absorption edge, which can be recovered with annealing at the glasstransition temperature. Bandgap light is effective in producing the redshift, 1,5 while subbandgap light can also induce some changes. 1,2,6 The photodarkening phenomenon is demonstrated to arise from photoinduced enhancement of randomness in amorphous structures, 7 while the entity of atomic change is still speculative.…”

Section: Introductionmentioning

confidence: 99%

“…1,2 In scientific respect, the phenomena are assumed to be caused through electron-lattice interaction in metastable disordered atomic structures, the subject not yet being understood. In addition, the phenomena are promising for optical applications.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Photoexpansion inAs2S3glass

Tanaka

1998

Phys. Rev. B

148

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Mechanisms of photoexpansion in chalcogenide glasses have been studied in three respects. A detailed x-ray investigation of As 2 S 3 shows that the photoexpansion can be connected with asymmetric broadening of the first sharp diffraction peak. Comparison between radiation-induced volume changes and density ratios of glassyto-crystalline forms in As 2 S 3 and SiO 2 implies that As 2 S 3 can expand since the glass is as dense as its crystal. When As 2 S 3 is exposed to illumination, the photoexpansion appears earlier and later than the photodarkening for bandgap and subbandgap illumination, respectively. These observations are discussed from a microscopic point of view. ͓S0163-1829͑98͒09209-1͔

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Photoexpansion inAs2S3glass

Tanaka

1998

Phys. Rev. B

148

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“…Amorphous chalcogenide glasses (ChGs) have emerged as promising candidates for all-photonic devices due to their high Kerr and third-order optical non-linearities that are two to three orders of magnitude greater than silica. 9,10 Apart from this, ChG also exhibits unique light-induced effects of fundamental interest like photoexpansion, 11 photofluidity, 12 which makes them versatile platforms for optoelectronics, waveguide writing, patterning, and nanofabrication. [13][14][15] In ChG, Kolomiets et al 16 and Matsuda et al 17 have demonstrated the transient change in photocurrent.…”

mentioning

confidence: 99%

Ultrafast defect dynamics: A new approach to all optical broadband switching employing amorphous selenium thin films

et al. 2015

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Optical switches offer higher switching speeds than electronics, however, in most cases utilizing the interband transitions of the active medium for switching. As a result, the signal suffers heavy losses. In this article, we demonstrate a simple and yet efficient ultrafast broadband all-optical switching on ps timescale in the sub-bandgap region of the a-Se thin film, where the intrinsic absorption is very weak. The optical switching is attributed to short-lived transient defects that form localized states in the bandgap and possess a large electron-phonon coupling. We model these processes through first principles simulation that are in agreement with the experiments.

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Photostructural Changes in Glassy Semiconductors: Franck-Condon and Relaxation Transitions in Negative-U Centers

Klinger

Halpern

Bass

2002

phys. stat. sol. (b)

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A consistent theory is presented of a mechanism for unusual photostructural changes observed in glassy semiconductors. The theory takes into account that in these materials negative-U centers are the basic charge carriers of which the electron ground state is formed by strong self-trapping of a singlet electron pair in a soft atomic mode in a glass. As a gap-light generated excited state of a negative-U center is related to a large atomic displacement in the soft mode, it is shown that metastable "defects" can indeed be created in the original structure. These are identified as the photostructural changes. The theory provides consistent answers to open basic questions. First calculations of the transition probabilities related to this phenomenon are presented.Introduction As is observed in many experiments [1, 2], light of frequency comparable to the frequency of the optical gap, w % E opt = h, can produce long-lived "photostructural changes" (PSC) in glassy semiconductors (GS), particularly in chalcogenide glasses, with the mobility-gap width E g % ð1 À 3Þ eV and E opt ' E g . Related substantial changes are produced in a variety of macroscopic physical and chemical properties of these glasses. A surprising effect was the "photodarkening" effect, gap-light induced decrease DE opt of the original optical gap width E opt by up to around 10%. Interesting anisotropic effects (e.g., dichroism, birefringence) associated with the PSC have also been revealed recently [1]. The nature of the PSC was one of the challenging problems in the physics of GS since they were discovered about three decades ago. A number of models, involving different assumptions concerning microscopic mechanisms, have been proposed to account in general for photo-induced metastable effects in semiconductors and insulators [3], in which the metastability was associated with generation of electronic excitations. However, as noted in some papers (e.g., [1], p. 481), such models, based on the assumption that adiabatic potentials of the local atomic configuration in an important atomic motion mode were different in its ground and light excited electron states, were merely plausible suggestions which accorded with known features of the effect. In fact, even for crystalline materials such models have been put on a proper theoretical footing only for defect generation in alkali halides and crystalline SiO 2 . In other cases, the important atomic mode, as well as the parameters of the local atomic configuration, actually were not well defined. For the PSC [1, 2, 4], such models postulated that the adiabatic potential in its ground and excited electron states consisted of a lower branch as a double-well potential (DWP) and an upper branch as a single-well potential, separated by a large split energy D with D= h ) w v , the vibration frequency. The process of creation and destruction of metastable defects was supposed to be due to competing

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Photoinduced effects and metastability in amorphous semiconductors and insulators

Cited by 594 publications

References 266 publications

Photoexpansion inAs2S3glass

Photoexpansion inAs2S3glass

Ultrafast defect dynamics: A new approach to all optical broadband switching employing amorphous selenium thin films

Photostructural Changes in Glassy Semiconductors: Franck-Condon and Relaxation Transitions in Negative-U Centers

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