Optically induced metastable paramagnetic states in amorphous semiconductors

Bishop, S. G.; Strom, U.; Taylor, P. C.

doi:10.1103/physrevb.15.2278

Cited by 264 publications

(34 citation statements)

References 38 publications

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“…At the same time, the two substances exhibit opposite trends in terms of intrinsic and light induced ESR response. 21,22,30,31 Such simultaneous trends are particularly vivid in the Ge x Se 1−x series 32 for 1/3 < x < 1/2, which exhibit coordination ranging from tetrahedral (smaller x) to distorted octahedral (larger x). In this series, the octahedral ordering seems to correlate with the separation between s and p bands 33,34 and light induced ESR, and anti-correlate with the presence of unpaired spins 31 and the glassforming ability.…”

Section: Ppσ-bonded Semiconductors: the Role Of The Secondary Ppσmentioning

confidence: 95%

Electronic structure and the glass transition in pnictide and chalcogenide semiconductor alloys. I. The formation of the ppσ-network

Zhugayevych

Lubchenko

2010

The Journal of Chemical Physics

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Semiconductor glasses exhibit many unique optical and electronic anomalies. We have put forth a semi-phenomenological scenario (J. Chem. Phys. 132, 044508 (2010)) in which several of these anomalies arise from deep midgap electronic states residing on high-strain regions intrinsic to the activated transport above the glass transition. Here we demonstrate at the molecular level how this scenario is realized in an important class of semiconductor glasses, namely chalcogen and pnictogen containing alloys. Both the glass itself and the intrinsic electronic midgap states emerge as a result of the formation of a network composed of σ-bonded atomic p-orbitals that are only weakly hybridized. Despite a large number of weak bonds, these ppσ-networks are stable with respect to competing types of bonding, while exhibiting a high degree of structural degeneracy. The stability is rationalized with the help of a hereby proposed structural model, by which ppσ-networks are symmetry-broken and distorted versions of a high symmetry structure. The latter structure exhibits exact octahedral coordination and is fully covalently-bonded. The present approach provides a microscopic route to a fully consistent description of the electronic and structural excitations in vitreous semiconductors.

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Section: Ppσ-bonded Semiconductors: the Role Of The Secondary Ppσmentioning

confidence: 95%

Electronic structure and the glass transition in pnictide and chalcogenide semiconductor alloys. I. The formation of the ppσ-network

Zhugayevych

Lubchenko

2010

The Journal of Chemical Physics

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“…In fact, the increases in the photocurrent and the absorption coefficient are quantitatively the same. The increase in the absorption spectra at low temperatures was originally discovered by Bishop et al, 22 and is referred to as ''photoinduced midgap absorption'' 2 since the absorption increase is prominent in the subband-gap spectral region.…”

Section: B Temperature Dependencementioning

confidence: 99%

“…2,22 First, the photoconductive enhancement in As 2 S 3 has disappeared with annealing at 200-300 K. Second, the photocurrent increase has been erased with illumination of subband-gap light. For instance, in As 2 S 3 , the photoconductive enhancement has mostly disappeared with illumination of 1.4 eV light.…”

Section: B Temperature Dependencementioning

confidence: 99%

Photocurrent enhancement in light-soaked chalcogenide glasses

Toyosawa

Tanaka

1997

Phys. Rev. B

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Photocurrent changes with light soaking have been studied in amorphous As 2 S͑Se,Te͒ 3 and Se and crystalline As 2 S 3 and Se at 10-300 K. In the chalcogenide glasses the photoconductive degradation occurs at 300 K, while at low temperatures photocurrents in subband-gap spectral regions increase with light soaking. In the crystalline samples, no such changes are detected. The photoconductive enhancement appears to be related to the photoinduced midgap absorption, and the microscopic mechanism is discussed in a unified way. The observations are also compared with those in the Staebler-Wronski effect in amorphous Si:H films.

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“…[1][2][3] To examine the mechanism, we may choose the simplest material, amorphous Se ͑a-Se͒, which exhibits three kinds of photoinduced phenomena: photocrystallization at ϳ350 K, 2,4,5 photodarkening and related changes at 100-300 K, [6][7][8] and photoinduced electron-spin resonance ͑ESR͒ signals at ϳ10 K. [9][10][11] However, the disordered structure consisting of entangled chains ͑and rings͒ held together by van der Waals forces [12][13][14] still makes the elucidation of photoelectroatomic processes difficult.…”

Section: Introductionmentioning

confidence: 99%

“…It should be mentioned that the present ESR result is contrastive to those previously reported. [9][10][11]18 For instance, a-Se does not give dark ESR signals, and illumination of bandgap light at cryogenic temperatures induces broad signals ͑ϳ20 mT͒ at g ϳ 2 with spin densities of 10 16 -10 19 cm −3 , which is ascribed to dangling bonds of Se.…”

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confidence: 99%

Selenium-loaded zeolite (ZSM-5): II. Photoinduced phenomena

Saitoh

Tanaka

2009

Journal of Applied Physics

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Photoinduced phenomena in Se-loaded ZSM-5 single crystals have been studied through electron-spin resonance, optical absorption, and photoluminescence spectroscopy. Marked exposure effects appear at room temperature. Upon illumination of visible light, an electron-spin signal at g Ϸ 2.00 increases by an order, subgap absorption of 10 3 cm −1 appears, and photoluminescence at subgap regions weakens to a half. Timescales of these photoinduced changes including recoveries are not the same, which suggests different origins for the three changes. The spin increase evinces bond scission in single Se chains.

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Optically induced metastable paramagnetic states in amorphous semiconductors

Cited by 264 publications

References 38 publications

Electronic structure and the glass transition in pnictide and chalcogenide semiconductor alloys. I. The formation of the ppσ-network

Electronic structure and the glass transition in pnictide and chalcogenide semiconductor alloys. I. The formation of the ppσ-network

Photocurrent enhancement in light-soaked chalcogenide glasses

Selenium-loaded zeolite (ZSM-5): II. Photoinduced phenomena

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