The photoluminescence(photoluminescence)spectra of PS(porous silicon)prepared via electrochemical etching are presented and analysed.The PL of samples was measured at various temperatures.The corresponding parameters ...The photoluminescence(photoluminescence)spectra of PS(porous silicon)prepared via electrochemical etching are presented and analysed.The PL of samples was measured at various temperatures.The corresponding parameters of peaks(energy,intensity and FWHM)were calculated using a fitting procedure,where the PL spectrum was approximated by a set of Gaussian peaks.This model is based on the presumption that the emission of photons in the PL process represents independent events.The optimal number of peaks used in the model was estimated,where the residuum of the approximation was used as a criterion.The low thermal dependence of energies in the PL spectra(blue shift)indicates the strong influence of defects on the position of corresponding PL maxima.The observed increase of energies of peaks with temperature requires additional explanation.展开更多
The paper deals with the complex refractive index and photoluminescence in the IR-VIS light region of two sample types （i） black p-type silicon （BSi） produced by the surface structure chemical transfer method usin...The paper deals with the complex refractive index and photoluminescence in the IR-VIS light region of two sample types （i） black p-type silicon （BSi） produced by the surface structure chemical transfer method using Pt catalytic mesh, and （ii） porous p-type silicon prepared by standard electrochemical etching. We present, compare, and discuss the values of the IR-VIS complex refractive index obtained by calculation using the Kramers-Kronig transformation and the photoluminescence properties thereof. The results indicate that differences between the optical properties of the BSi and the porous Si are given by （a） the oxidation procedure of BSi, （b） the thickness of the formed black and porous Si layer, and by （c） the porosity of both layer types. We assume that the photoluminescence signal generated by oxidized BSi structures can be mainly related to the quantum confinement effect, while the photoluminescence of the porous p-type Si is caused by the optical activity of the SiOxHy compounds covering its surface region.展开更多
Progress in the manufacturing of the 2nd generation of electrical conductors based on high-temperature superconducting(HTS)compounds,commonly known as coated conductors(CC),has sparked interest in various fields of ap...Progress in the manufacturing of the 2nd generation of electrical conductors based on high-temperature superconducting(HTS)compounds,commonly known as coated conductors(CC),has sparked interest in various fields of application,including large magnetic systems for nuclear fusion and particle accelerators.To achieve the required electrical transport capacity in the kA range,tens of tapes must be assembled into a cable.Then,knowing the vulnerability of individual tapes to mechanical deformation is essential.We studied the behaviour of filamentized CC tapes with REBCO layer deposited on patterned substrate.Before this study,it was not clear whether such superconductor filamentization would affect the minimum core diameter,Dc,min,at which it still retains the transport capability.In the first stage,a set of 12 mm wide research samples,prepared with various number of filaments,underwent off-axis bending tests.Microstructural investigation then enabled understanding of the observed fact that the filamentary architecture did not cause any visible loss of transporting capability.In the study continuation,we compared the off-axis bending performance of short samples taken from 4 mm wide tapes produced industrially in lengths exceeding 100 m.Encouragingly,these filamentized tapes exhibited an endurance comparable to that of an equivalent non-filamentized tapes.Finally,in the last part of the study,simple models of round cables containing longer pieces(30 cm)of filamentized tape wrapped around a round core were tested.Some deterioration of performance was observed,relative to previous tests when only~1 cm long portion of tape was affected.Nevertheless,the observed 100%retention of critical current when bending the 4 mm wide filamentized tape on a 5.5 mm central core represents an important input to further discussion about adopting filamentized tapes,thanks to their better electromagnetic behaviour,in cables for future nuclear fusion reactors and particle accelerator magnets.展开更多
文摘The photoluminescence(photoluminescence)spectra of PS(porous silicon)prepared via electrochemical etching are presented and analysed.The PL of samples was measured at various temperatures.The corresponding parameters of peaks(energy,intensity and FWHM)were calculated using a fitting procedure,where the PL spectrum was approximated by a set of Gaussian peaks.This model is based on the presumption that the emission of photons in the PL process represents independent events.The optimal number of peaks used in the model was estimated,where the residuum of the approximation was used as a criterion.The low thermal dependence of energies in the PL spectra(blue shift)indicates the strong influence of defects on the position of corresponding PL maxima.The observed increase of energies of peaks with temperature requires additional explanation.
文摘The paper deals with the complex refractive index and photoluminescence in the IR-VIS light region of two sample types （i） black p-type silicon （BSi） produced by the surface structure chemical transfer method using Pt catalytic mesh, and （ii） porous p-type silicon prepared by standard electrochemical etching. We present, compare, and discuss the values of the IR-VIS complex refractive index obtained by calculation using the Kramers-Kronig transformation and the photoluminescence properties thereof. The results indicate that differences between the optical properties of the BSi and the porous Si are given by （a） the oxidation procedure of BSi, （b） the thickness of the formed black and porous Si layer, and by （c） the porosity of both layer types. We assume that the photoluminescence signal generated by oxidized BSi structures can be mainly related to the quantum confinement effect, while the photoluminescence of the porous p-type Si is caused by the optical activity of the SiOxHy compounds covering its surface region.
基金supported by the grant agency VEGA under contract 2/0098/24the grant agency APVV under contract APVV-20-0056by the EU NextGenerationEU through the Recovery and Resilience Plan for Slovakia under the project No.09I04-03-V04-00020.
文摘Progress in the manufacturing of the 2nd generation of electrical conductors based on high-temperature superconducting(HTS)compounds,commonly known as coated conductors(CC),has sparked interest in various fields of application,including large magnetic systems for nuclear fusion and particle accelerators.To achieve the required electrical transport capacity in the kA range,tens of tapes must be assembled into a cable.Then,knowing the vulnerability of individual tapes to mechanical deformation is essential.We studied the behaviour of filamentized CC tapes with REBCO layer deposited on patterned substrate.Before this study,it was not clear whether such superconductor filamentization would affect the minimum core diameter,Dc,min,at which it still retains the transport capability.In the first stage,a set of 12 mm wide research samples,prepared with various number of filaments,underwent off-axis bending tests.Microstructural investigation then enabled understanding of the observed fact that the filamentary architecture did not cause any visible loss of transporting capability.In the study continuation,we compared the off-axis bending performance of short samples taken from 4 mm wide tapes produced industrially in lengths exceeding 100 m.Encouragingly,these filamentized tapes exhibited an endurance comparable to that of an equivalent non-filamentized tapes.Finally,in the last part of the study,simple models of round cables containing longer pieces(30 cm)of filamentized tape wrapped around a round core were tested.Some deterioration of performance was observed,relative to previous tests when only~1 cm long portion of tape was affected.Nevertheless,the observed 100%retention of critical current when bending the 4 mm wide filamentized tape on a 5.5 mm central core represents an important input to further discussion about adopting filamentized tapes,thanks to their better electromagnetic behaviour,in cables for future nuclear fusion reactors and particle accelerator magnets.
