Temperature variation of optical absorption edge in Sn2P2S6and SnP2S6crystals

Studenyak, I.P.; Mitrovcij, V. V.; Kovács, Gy.; Mykajlo, O.; Гурзан, М. І.; Vysochanskiǐ, Yu. M.

doi:10.1080/00150190108215009

Cited by 27 publications

(20 citation statements)

References 19 publications

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“…In the measurements reported in [21] it seems that the axes were defined differently, because the Urbach parameters given there would qualitatively match with our results if the polarizations x and y were exchanged. The difference in the absorption values obtained there might be related to a possible different crystal composition.…”

Section: 1supporting

confidence: 75%

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Determination of the absorption constant in the interband region by photocurrent measurements

et al. 2006

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We determined high absorption constants of crystals from photocurrent measurements within the interband absorption region (10-10 4 cm −1 ). The method has been demonstrated in the interband absorption regime near 530 nm in Sn 2 P 2 S 6 , a novel infrared sensitive photorefractive material, and in the interband absorption regime near 257 nm of near stoichiometric LiTaO 3 . Besides the verification of older measurements with our new technique, precise absorption data for Sn 2 P 2 S 6 in the wavelength range 488-514 nm are presented. Light emitting diodes, photodetectors, electroabsorption modulators [1], solar cells and many other photonic devices involve transitions of charges between bands, and thus work in a region of high light absorption. Also holographic applications based on the interband photorefractive effect such as multiple quantum well devices [2,3], incoherent-to-coherent optical converters [4], light-induced waveguides [5], high-frame-rate joint Fourier-transform correlators [6] and dynamically reconfigurable wavelength filters [7], operate beyond the absorption edge with absorption constants up to 10 3 cm −1 . In this region, the absorption constant is not easily measured, but is nevertheless of crucial importance for the underlying basic physical mechanisms and the applications.The most common technique for measuring absorption constants in the order of 10-10 4 cm −1 is a direct measurement of the transmission of a thin sample. This method is quite precise but often requires a thin plate of only a few µm thickness.If the light at the wavelength of interest induces a secondary physical effect, it is possible to determine the absorption constant indirectly by a scanning method. For example,

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Section: 1supporting

confidence: 75%

“…In Sn 2 P 2 S 6 crystal optical correlation at high repetition rates has been demonstrated [6] using interband recording at a wavelength of 532 nm using frequency doubled Nd:YAG laser. In the interband region the absorption constant has been previously calculated using the Urbach rule [20,21].…”

Section: Experimental Verificationmentioning

confidence: 99%

Determination of the absorption constant in the interband region by photocurrent measurements

et al. 2006

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“…The shape of the absorption edge is an important characteristic. For the case of Sn 2 P 2 S 6 crystals and their analogs it has been studied in the works [11][12][13][14][15][16][17]. In particular, it has been demonstrated in Ref.…”

Section: Fundamental Absorption Edge and The Urbach Rulementioning

confidence: 99%

“…Later on, the structure of energy bands has been calculated, thus evidencing that Sn 2 P 2 S 6 represents a direct-band semiconductor [19]. At the same time, the studies [13][14][15][16][17] ascertained that the high-energy part of the absorption edge for the Sn 2 P 2 S 6 -type crystals obeys the Urbach rule. In this relation we would stress that the same is true for a number of perovskites [19] and the SbSJ-type crystals [20].…”

Section: Fundamental Absorption Edge and The Urbach Rulementioning

confidence: 99%

Optical properties of A2B2C6 ferroelectrics-semiconductors: the effect of temperature and hydrostatic pressure

Герзанич¹

2008

Ukr. J. Phys. Opt.

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In this review the results of experimental studies for the influence of temperature and high pressure on the fundamental absorption edge, optical birefringence and vibrational spectra of IV V VI 2 2 6A B C -group crystals are presented. It is revealed that the high-energy part of the absorption edge is described by the Urbach rule, while its low-energy part is formed by indirect optical transitions. Violation of the Urbach rule is detected in the region of incommensurate phase. The temperature and baric coefficients of the forbidden gap in the ferroelectric, paraelectric and incommensurate phases are found to be negative. Electronphonon interaction plays a major part in the temperature changes of the bandgap. According to the theory, the bandgap suffers characteristic anomalies that depend upon the phase transition order. The critical indices of the order parameter and heat capacity and the Landau-Ginzburg expansion coefficients derived from the baric studies of optical birefringence agree well with a presence of Lifshitz point at the р,Т-diagrams of the crystals under test. Relative shift in the frequencies of the Raman spectra occurring under mechanical stresses testifies a notable nonequivalence of atomic bonds and a possibility of dividing the vibrations in Sn 2 P 2 S 6 into the external and internal ones. The results of baric investigations of the Raman spectra show that the structural transformation in Sn 2 P 2 S 6 is mainly linked to Sn-S bonds. The results analysed by us testify a possibility for practical applications of Sn 2 P 2 S 6 ferroelectrics as a converter of coherent long-wave radiation into shorter-wave one.

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“…At ambient pressure, the Sn 2 P 2 S 6 crystal undergoes a second-order structural transition from the ferroelectric phase (Pn) to the paraelectric (P2 1 /n) one at 337 K, which was thoroughly investigated by X-ray diffraction [5], dielectric studies [6], Raman scattering [7][8][9], inelastic neutron scattering [10], ultrasonic measurements [11], optical spectroscopy [12], birefringence measurements [13], Mössbauer spectroscopy [14,15], X-ray photoelectron spectroscopy [16,17], soft X-ray fluorescence spectroscopy [16], and thermal expansion studies [18]. In most cases, these studies were carried out for good quality bulk single crystals.…”

Section: Introductionmentioning

confidence: 99%

Annealing-induced formation of Sn2P2S6 crystallites in As2S3-based glass matrix

Azhniuk¹

2015

Semicond. Phys. Quantum Electron. Optoelectron.

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Abstract. Sn-As-P-S glasses were obtained using co-melting of pre-synthesized As 2 S 3 and Sn 2 P 2 S 6 . Their structure and composition were confirmed by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, and micro-Raman scattering. Crystallization of Sn 2 P 2 S 6 crystallites from the glass matrix is observed at annealing under relatively low temperatures (410…580 K).

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Temperature variation of optical absorption edge in Sn₂P₂S₆and SnP₂S₆crystals

Cited by 27 publications

References 19 publications

Determination of the absorption constant in the interband region by photocurrent measurements

Determination of the absorption constant in the interband region by photocurrent measurements

Optical properties of A2B2C6 ferroelectrics-semiconductors: the effect of temperature and hydrostatic pressure

Annealing-induced formation of Sn2P2S6 crystallites in As2S3-based glass matrix

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