Structural phototransformations in thin selenium films

Hansen, Steven G.; Robitaille, T. E.

doi:10.1016/0040-6090(87)90013-7

Cited by 6 publications

(5 citation statements)

References 12 publications

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“…It would be instructive to comment on the fact that these results were not expected in view of the following reasons: (1) the photoplastic effect 1 which is one of the important conditions of mass-transport appearence, 10 should, in principle, be very weak in a-Se due to low glass formation temperature (T g % 40 C) and (2) photocrystallization may also occur for long-term irradiation. 16,17 The last process would impede the displacement of material over atomic distances and hence the SRG height should reach saturation levels over an extended time of laser irradiation, which contradicts the linear height vs. time dependence observed experimentally [ Fig. 1(c , we have observed the same behavior as presented in Fig.…”

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confidence: 48%

“…Several studies have shown that photocrystallization occurs in a-Se films under long-term exposure by singlebeam bandgap light. 16,17 On the contrary, in the present investigation of holographic recording, we observe decrease of the roughness instead of its evolution to crystallites. SRG I transforms into transient light-induced SRG with M-shape profile, which is further replaced by SRG II (see Fig.…”

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confidence: 44%

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Photoinduced mass-transport based holographic recording of surface relief gratings in amorphous selenium films

Trunov

Lytvyn

Yannopoulos

et al. 2011

Applied Physics Letters

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Surface relief gratings formation in amorphous selenium thin films in two recording configurations with light intensity modulation were studied in situ by real-time atomic force microscopy and diffraction efficiency measurements. We report observation of mass transport effect in films induced by band-gap irradiation when the light polarization of the recording beams has a component along the light intensity gradient ("p-p" scheme of recording) that allows obtaining giant stable gratings in this versatile chalcogenide material. On the contrary, only a pure scalar weak grating caused by photoinduced volume shrinkage is obtained in the "s-s" recording configuration, even for long-term irradiation. Chalcogenide glasses (ChG) are known to exhibit a rich variety of photoinduced changes when illuminated with near bandgap light including changes in mechanical properties, termed as photoplastic effects.1 Among them, the effect of light induced surface deformation and direct fabrication of surface relief gratings (SRGs) in ChG is intensively studied over the last decade both experimentally 2-10 and theoretically.11 Two main types of SRG induced by holographic recording, due to the excitation intensity modulation, with near band-gap light in ChG can be distinguished according to their formation mechanism and their properties:10 (1) small scalar SRG induced by either volume expansion or shrinkage due to different response of the material in the bright and dark zones of the interference pattern formed and (2) giant vectorial SRG induced by lateral mass transport in the case where the light polarization of the recording beams has a component along the light intensity gradient.Experiments have shown that only few compositions of ChG demonstrate both types of SRG. For example, vectorial SRG have been observed only for Se-rich films in the binary As-Se system (As 20 Se 80 ) 10 and for the compositions close to As 40 S 60 in As-S glasses 3 while scalar SRGs are common to all glass compositions of As-S and As-Se glasses. While for As-S glass the above observation (lack of vectorial SRG) could be accounted for by considering the photo-induced polymerization effect in S-rich compositions, 12 in the case of As-Se glasses the effect is not yet well understood. Although elemental amorphous Se (a-Se) is a model glass-former in chalcogenide science, no systematic studies of SRG formation have been carried out up to now, while investigations of other photoinduced effects abound. 13 A fact that perplexes studies of SRG formation relates to the photoinduced crystallization of a-Se (Ref. 14) under band-gap illumination, thus preventing the formation of advanced surface relief stable in time.Few papers report the formation of surface relief induced by holographic recording for a-Se films. 2,5,15 In an early study, Haro-Poniatowski et al.,15 employing phase conjugation, haveshown that small (20 nm in height) photoinduced surface relief gratings appears in 4 lm-thick films with the same spatial period. Slightly higher reliefs ($ 40 nm) formed a...

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contrasting

confidence: 48%

contrasting

confidence: 44%

Photoinduced mass-transport based holographic recording of surface relief gratings in amorphous selenium films

Trunov

Lytvyn

Yannopoulos

et al. 2011

Applied Physics Letters

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“…Chand et al [4] have reported on the thermally stimulated discharge current behaviour of native and irradiated a-Se films. Hansen et al [5] have investigated the photocoagulation process in amorphous selenium thin films.…”

Section: Introductionmentioning

confidence: 99%

Amorphous selenium thin films prepared using chemical bath deposition: optimization of the deposition process and characterization

Bindu

Lakshmi

Bini

et al. 2002

Semicond. Sci. Technol.

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Amorphous selenium films were prepared at room temperature using the simple and safe method of chemical bath deposition. This was achieved with an acidified solution of Na 2 SeSO 3 at a pH value of 4.5. In order to confirm the formation of amorphous selenium (a-Se), samples were characterized using x-ray diffraction, x-ray photoelectron spectroscopy, secondary ion mass spectroscopy and optical absorption studies. The optical bandgap of the material was found to be 2.09 eV. Indium selenide could be prepared by annealing this a-Se in a multilayer structure glass/SnO 2 /a-Se/In.

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“…The mechanism of photocrystallization is believed to be photoelectronic; i.e., amorphous-to-crystalline structural changes are enhanced by photoexcited carriers, while the details of the electron-lattice interaction are still ambiguous. [6][7][8][9] On the other hand, Zhdanov et al have discovered that optical anisotropy can be induced in chalcogenide glasses subjected to the exposure of linearly polarized light. 5 For instance, in As 2 S 3 , illumination of linearly polarized light at room temperature can induce a dichroic shift of ϳ5 meV in the optical absorption edge and a birefringence of ϳ0.002.…”

Section: Introductionmentioning

confidence: 99%