Persistent photoconductivity in high-temperature superconductors with nano-scale fragmented copper-oxide chains

Markowitsch, W.; Brantner, P.; Stockinger, C.; Lang, W.; Siraj, K.; Pedarnig, J.D.; Bäuerle, D.

doi:10.1016/j.jnoncrysol.2005.12.058

Cited by 5 publications

(6 citation statements)

References 12 publications

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“…PPC has been observed in high temperature superconductors, as seen in the above image, which shows the relaxation of PPC in YB 2 C 3 O 6.6 (YBCO) [117] at four different temperatures and matches well with a stretched exponential function (as shown in figure 10). A long term stretched exponential above 250 K is due to the photoinduced excess conductivity in oxygen deficient YBCO.…”

Section: Ppc In Superconductorssupporting

confidence: 65%

A review on realizing the modern optoelectronic applications through persistent photoconductivity

Sumanth¹,

Ganapathi²,

Rao³

et al. 2022

J. Phys. D: Appl. Phys.

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Optoelectronic devices are becoming increasingly important due to their compatibility with CMOS fabrication technology and their superior performance in all dimensions compared to currently available devices. Numerous modern applications are formulated based on various aspects of optoelectronic materials and devices, such as artificial intelligence, optical memory, optoelectronic synapses, humanoid-photodetectors, holography, solar cells, charge storage devices, bio-electronic devices, and so on. Persistent photoconductivity (PPC), an optoelectronic phenomenon that has piqued the scientific community's interest, is a novel approach to these modern applications. In this article, we highlighted the use of PPC in a variety of emerging optoelectronic applications. PPC is a light-induced mechanism that persists after light excitation is terminated, i.e., the response does not stop immediately but remains available for a period of time. In recent years, the time duration over which the response after turning off the illumination is available has been proposed for a variety of applications. PPC has primarily been explored from a theoretical point of view, with the application component being largely ignored. Very recently, the scientific community has started exploring the possible applications pertaining to PPC such as optoelectronic synapses, holography, optical memory, bioelectronics, and artificial intelligence. Depending on the nature of the material and the type of model used in the application, a variety of mechanisms can be used to modulate the charge trapping and de-trapping methodologies for a specific application. This topical review summarizes the origins of PPC, its control mechanism, and recent advances in a variety of materials such as metal oxides, superconductors, nanofibers, 2D-semiconductors, alloys, nitrides, organic materials, topological insulators, and so on. In addition, the paper has carefully explored the development of next-generation optoelectronic applications designed for industry 4.0 leveraging the PPC phenomenon.

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Section: Ppc In Superconductorssupporting

confidence: 65%

A review on realizing the modern optoelectronic applications through persistent photoconductivity

Sumanth¹,

Ganapathi²,

Rao³

et al. 2022

J. Phys. D: Appl. Phys.

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“…In PPC relaxation experiments [2,3,5], the time constant τ depends exponentially on temperature, according to equation (2).…”

Section: Behaviour Of the Stretched-exponential Parametersmentioning

confidence: 99%

“…β varies nearly linear as a function of T , assuming values from (approximately) 0.4 to 0.6 in semiconducting samples [2,3] and 0.5 to 0.7 in metallic samples [5]. β is usually interpreted as a merely statistical parameter that measures the distribution width of energy barriers, which the carriers have to overcome in the relaxation process.…”

Section: Behaviour Of the Stretched-exponential Parametersmentioning

confidence: 99%

“…For photodoping, S is the electrical resistance R, and for PPC relaxation it is given by the electrical conductivity σ . The PPC relaxation, occurring only at temperatures close to room temperature and above, has been extensively studied [2][3][4][5]. It was established that τ in these relaxation data shows the typical exponential temperature dependence of a thermally activated process, given by…”

Section: Introductionmentioning

confidence: 99%

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Photodoping of YBa₂Cu₃O_x: dependence on temperature and photon energy

Markowitsch

Brantner

Lang

et al. 2008

Supercond. Sci. Technol.

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We present studies of the photodoping process in underdoped metallic YBa2Cu3Ox, where x≈6.6. Measurements of the time-dependent electrical resistivity during photoexcitation were performed at several temperatures and with two different lasers as the light source. The effect of photodoping on the samples was characterized by the resistivity reduction ΔR(N)/R(0) and by the enhancement ΔTc of the superconducting transition temperature for a fixed photon dose of N = 1.2 × 1023 cm−2. At low temperatures, we observed a large ΔR(N)/R(0) but a small ΔTc. In the intermediate temperature range, both quantities were relatively small. At the highest studied temperature (270 K), ΔTc reached the largest values in these experiments, and ΔR(N)/R(0) was almost as large as at low temperatures. Interestingly, only at low temperatures did we observe a significant dependence of ΔR(N)/R(0) on the laser wavelength λ, whereas ΔTc is essentially independent of λ. The time dependence of the resistivity during the photoexcitation showed a stretched-exponential decrease at all temperatures, with values of the dispersion parameter β between 0.3 and 0.55, which are distinctly smaller than observed in persistent photoconductivity relaxation in YBa2Cu3Ox. β was essentially the same for the two laser wavelengths and showed only a weak temperature dependence. We observed a tendency of β towards smaller values (≈0.4) at low temperatures and to slightly higher values (≈0.5) above approximately 200 K. We interpret this finding within a microscopic theory of the stretched-exponential parameters, and conclude that there is a long-range interaction between the photoexcited electrons and the chain defects, which act as trapping centres and that the traps become mobile at high temperatures.

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“…Persistent photo-induced changes in oxygen-deficient YBCO were also observed in optical [11], infrared [12] and Raman studies [13,14]. Most remarkable is the extremely slow relaxation of the photoenhanced state, showing decay times of several hours or days even at room temperature [15][16][17] and slightly above. At temperatures lower than about 250 K, the effect is completely persistent.…”

Section: Introductionmentioning

confidence: 97%

Persistent photoconductivity in oxygen-deficient and ion-irradiated YBa₂Cu₃O_x

Markowitsch

Lang

Pedarnig

et al. 2009

Supercond. Sci. Technol.

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The persistent photoconductivity (PPC) in oxygen-deficient YBa 2 Cu 3 O x (YBCO) has many peculiar features. The illumination of YBCO with visible light or ultraviolet radiation leads to significant changes in the electronic properties: the free carrier concentration increases, the carrier mobility changes and, in metallic samples, the superconducting transition temperature T c increases. Most intriguing is the persistence of the photo-induced effects up to surprisingly high temperatures. Below 250 K, PPC relaxation is practically unobservable and, at higher temperatures, the decay of the photo-induced changes takes hours or even days to complete. This temperature stability has stimulated the term photodoping for the photo-induced changes. Our studies have shown a pronounced dependence of the photodoping results on the temperature at which the experiment is performed. Hall effect studies demonstrated that the changes of the carrier concentration and of the mobility are completely different at high temperatures compared to lower temperatures. The photo-induced T c increase was twice as large at high temperatures. Also, at high temperatures, our mobility data very clearly show the sign of a competition between two processes that contribute to the photodoping. We have identified one of the processes as photo-assisted oxygen ordering within the chain layer of YBCO. The investigation of the PPC effect was noticeably promoted by a new technique of growing YBCO thin films on so-called off-axis oriented substrates. From photodoping experiments on such films, the photo-induced changes of the in-plane ρ ab and of the out-of-plane ρ c resistivities were derived. Both resistivity components decrease under illumination with light, but asynchronously, so the electronic anisotropy ρ c /ρ ab gradually changes during the illumination. Our results are consistent with previously proposed models of the PPC based on the charge transfer from the copper-oxide planes to the copper-oxide chains. We obtained evidence that this process is accompanied by a re-arrangement of the oxygen atoms and/or oxygen vacancies in the chain layer. The latter process seems to be more pronounced at high temperatures, most likely because of the higher mobility of the oxygen atoms at those temperatures.Very recent results from the photo-excitation of ion-irradiated samples indicate that the observed photo-induced changes have a different origin than the PPC in oxygen-deficient YBCO.

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Persistent photoconductivity in high-temperature superconductors with nano-scale fragmented copper-oxide chains

Cited by 5 publications

References 12 publications

A review on realizing the modern optoelectronic applications through persistent photoconductivity

A review on realizing the modern optoelectronic applications through persistent photoconductivity

Photodoping of YBa₂Cu₃O_x: dependence on temperature and photon energy

Persistent photoconductivity in oxygen-deficient and ion-irradiated YBa₂Cu₃O_x

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Persistent photoconductivity in high-temperature superconductors with nano-scale fragmented copper-oxide chains

Cited by 5 publications

References 12 publications

A review on realizing the modern optoelectronic applications through persistent photoconductivity

A review on realizing the modern optoelectronic applications through persistent photoconductivity

Photodoping of YBa2Cu3Ox: dependence on temperature and photon energy

Persistent photoconductivity in oxygen-deficient and ion-irradiated YBa2Cu3Ox

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Product

Resources

About

Photodoping of YBa₂Cu₃O_x: dependence on temperature and photon energy

Persistent photoconductivity in oxygen-deficient and ion-irradiated YBa₂Cu₃O_x