Unusual memory effects in an incommensurate phase of the TlInS2 ferroelectric semiconductor

Seyidov, M. H. Yu.; Suleymanov, Rauf A.; Salehli, F.; Babayev, S. S.; Mammadov, T. G.; Nadjafov, A. I.; Sharifov, G. M.

doi:10.1134/s1063783409030226

Cited by 9 publications

(4 citation statements)

References 16 publications

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“…It is known that, after initial polarization of TlInS 2 :La ferroelectric-semiconductors in bias field, the internal electric field originated from hetero-and homocharges may be caused by temporary residual space charges accumulated in the trap levels in the regions directly adjacent to the electrodes (surface electric field) as well as in bulk region of the crystal. 18,19 An internal electric field created by homocharges formed in the bulk region of crystal has the direction opposite to the direction of applied polarity. Using the short-circuit technique, we can separate the TSDC response from internal electric fields which are built in the bulk region of TlInS 2 :La crystal.…”

Section: Resultsmentioning

confidence: 99%

“…5, small peaks are well identified at $208 and $215 K corresponding to anomalies at T i and inside the IC-phase. 19 However, it needs to be pointed out that average polarization inside IC-phase must be zero because the IC-phase possesses the center of inversion symmetry. 10,11 This means that, during poling process, the external electric field does not induce aligned polarization inside IC-phase.…”

Section: Resultsmentioning

confidence: 99%

“…Recent studies have presented experimental evidence and discussed on possible theoretical models for the formation of electrets state in these materials, especially inside the region of IC-phase. 18,19,30,31 The nature of electrets state in TlInS 2 or TlGaSe 2 crystals is related to deep level defects within the temperature activation region that includes the IC-phase. Due to a lack of translational symmetry, TlInS 2 or TlGaSe 2 layered crystals within the temperature region of the existence of IC-modulated phase are the examples of aperiodic or quasiperiodic crystals, i.e., the basic structure with space group symmetry has a periodic modulation with wave vectors not belonging to the reciprocal lattice of the basic structure.…”

Section: Discussion Of Experimental Resultsmentioning

confidence: 99%

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Characterization of deep level defects and thermally stimulated depolarization phenomena in La-doped TlInS2 layered semiconductor

Seyidov

Suleymanov

Mikailzade

et al. 2015

Journal of Applied Physics

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Lanthanum-doped high quality TlInS 2 (TlInS 2 :La) ferroelectric-semiconductor was characterized by photo-induced current transient spectroscopy (PICTS). Different impurity centers are resolved and identified. Analyses of the experimental data were performed in order to determine the characteristic parameters of the extrinsic and intrinsic defects. The energies and capturing cross section of deep traps were obtained by using the heating rate method. The observed changes in the Thermally Stimulated Depolarization Currents (TSDC) near the phase transition points in TlInS 2 :La ferroelectric-semiconductor are interpreted as a result of self-polarization of the crystal due to the internal electric field caused by charged defects. The TSDC spectra show the depolarization peaks, which are attributed to defects of dipolar origin. These peaks provide important information on the defect structure and localized energy states in TlInS 2 :La. Thermal treatments of TlInS 2 :La under an external electric field, which was applied at different temperatures, allowed us to identify a peak in TSDC which was originated from La-dopant. It was established that deep energy level trap BTE43, which are active at low temperature (T 156 K) and have activation energy 0.29 eV and the capture cross section 2.2 Â 10 À14 cm 2 , corresponds to the La dopant. According to the PICTS results, the deep level trap center B5 is activated in the temperature region of incommensurate (IC) phases of TlInS 2 :La, having the giant static dielectric constant due to the structural disorders. From the PICTS simulation results for B5, native deep level trap having an activation energy of 0.3 eV and the capture cross section of 1.8 Â 10 À16 cm 2 were established. A substantial amount of residual space charges is trapped by the deep level localized energy states of B5 in IC-phase. While the external electric field is applied, permanent dipoles, which are originated from the charged B5 deep level defects, are aligned in the direction of the applied electric field and the equilibrium polarization can be reached in a relatively short time. When the polarization field is maintained, while cooling the temperature of sample to a sufficiently low degrees, the relaxation times of the aligned dipoles drastically increases. Practically, frozen internal electric field or electrets states remain inside the TlInS 2 :La when the applied bias field is switched off. The influence of deep level defects on TSDC spectra of TlInS 2 :La has been revealed for the first time. V C 2015 AIP Publishing LLC.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Discussion Of Experimental Resultsmentioning

confidence: 99%

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Characterization of deep level defects and thermally stimulated depolarization phenomena in La-doped TlInS2 layered semiconductor

Seyidov

Suleymanov

Mikailzade

et al. 2015

Journal of Applied Physics

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“…The pinning of the modulation waves on defects can be mentioned as an example of the influence . These waves explain memory effects in TlInS 2 crystals as well as their relaxation properties . It should be noted that the defect subsystem can be modified by irradiating of a crystal with electrons and γ‐radiation.…”

Section: Introductionmentioning

confidence: 99%

The effect of X-ray irradiation on formation and decay of the incommensurate phase in TlInS₂crystals

Nikolaienko

Zloi

Isaiev

et al. 2016

Phys. Status Solidi B

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The influence of the X‐ray irradiation on the crystal structure of TlInS2 C and 2C polytypes were studied by single‐crystal X‐ray diffraction method. The scanning of the reciprocal space in the planes (0kl)*, (h0l)*, (hhl)* were carried out for initial and irradiated samples (absorbed doses are 0.9 and 2.9 kGy) in the temperature range 180–300 K. It was found that after irradiation, the incommensurate phase satellites q(−δ, 0, +0.25) and q(+δ, 0, −0.25) (δ = 0.04) were observed even at room temperature in the C‐TlInS2 samples. Their intensities vary in direct proportion to the dose and significantly differ from each other. The 10 h annealing at 430 K completely destroyed these incommensurate structures. The temperature dependences of the incommensurate and commensurate phases volume fractions were obtained for unirradiated, irradiated, and annealed C‐TlInS2 samples. The modulation satellites of the incommensurate and commensurate phases were not observed in the temperature range of 180–300 K in the irradiated as well as unirradiated samples of the 2C‐polytype TlInS2. The role of defect density waves in the formation of the modulated structures in the irradiated TlInS2 crystals is discussed.

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Anisotropic optical constants and inter-band optical transitions in layered semiconductor TlGaSe2

Shim

Itoh

Wakita

et al. 2017

Applied Surface Science

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Unusual memory effects in an incommensurate phase of the TlInS2 ferroelectric semiconductor

Cited by 9 publications

References 16 publications

Characterization of deep level defects and thermally stimulated depolarization phenomena in La-doped TlInS2 layered semiconductor

Characterization of deep level defects and thermally stimulated depolarization phenomena in La-doped TlInS2 layered semiconductor

The effect of X-ray irradiation on formation and decay of the incommensurate phase in TlInS₂crystals

Anisotropic optical constants and inter-band optical transitions in layered semiconductor TlGaSe2

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Unusual memory effects in an incommensurate phase of the TlInS2 ferroelectric semiconductor

Cited by 9 publications

References 16 publications

Characterization of deep level defects and thermally stimulated depolarization phenomena in La-doped TlInS2 layered semiconductor

Characterization of deep level defects and thermally stimulated depolarization phenomena in La-doped TlInS2 layered semiconductor

The effect of X-ray irradiation on formation and decay of the incommensurate phase in TlInS2crystals

Anisotropic optical constants and inter-band optical transitions in layered semiconductor TlGaSe2

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The effect of X-ray irradiation on formation and decay of the incommensurate phase in TlInS₂crystals