Nonequilibrium carrier recombination in highly excited epitaxial layers of 4H–SiC and free standing 3C–SiC was analyzed numerically studied experimentally by the time-resolved absorption (FCA) technique. The measurement setup combined interband excitation a picosecond laser pulse probing dynamics at excess densities ΔN=1017–1020 cm−3 range optically or electronically delayed probe pulses, thus providing temporal resolution 10 ps ns, respectively. FCA decay kinetics different levels...

The aim of this study was to evaluate the inactivation efficiency Listeria monocytogenes ATC(L3) C 7644 and Salmonella enterica serovar Typhimurium strain DS88 by combined treatment hypericin (Hyp)-based photosensitization high power pulsed light (HPPL).Cells were incubated with Hyp (1 × 10(-5) or 1 10(-7) mol l(-1)) in PBS illuminated a λ = 585 nm. For treatment, bacteria were, after photosensitization, exposed 350 pulses HPPL (UV dose 0·023 J cm(-2)). Fluorescence measurements performed...

Journal Article Advanced high‐power pulsed light device to decontaminate food from pathogens: effects on Salmonella typhimurium viability in vitro Get access Z. Luksiene, Luksiene Institute of Materials Science and Applied Research, Vilnius University, Vilnius, Lithuania Sauletekio 10, LT‐10223, Lithuania. E‐mail: Zivile.Luksiene@mtmi.vu.lt Search for other works by this author on: Oxford Academic Google Scholar V. Gudelis, Gudelis I. Buchovec, Buchovec J. Raudeliuniene Microbiology, Volume...

Abstract We demonstrate applicability of time‐resolved free‐carrier absorption and transient grating techniques for investigation carrier recombination diffusion features in a bulk diamond. Carrier injection into 1 mm thick, IIa type high‐pressure high‐temperature grown layer was realized by two‐photon ∼5 ps laser pulse at 351 nm wavelength. Kinetics differential transmission 80–800 K range various excess densities provided lifetimes 360 ns room temperature their dependences. A linear...

A holographic beam splitter has been integrated into a picosecond four-wave mixing (FWM) scheme. This modification significantly simplified the procedure of dynamic grating recording, thus making FWM technique an easy-to-use tool for characterization wide band gap materials. The novel scheme was applied hydride vapor phase epitaxy-grown undoped GaN layers different thickness. It allowed determination carrier lifetime, diffusion coefficient, and length by optical means, as well study...

Abstract We report investigation of carrier recombination and diffusivity in bulk diamonds different crystalline structure – microcrystalline (MC) CVD‐grown single HPHT diamonds. Presence neutral positively charged nitrogen hydrogen defects was determined from NIR UV–IR absorption spectra. Carrier injection into 1‐mm thick layers realized by two‐photon at 351 nm wavelength. lifetimes 150–330 ns IIa type crystals correlated with N density, while the CVD crystal exhibited very fast (80 ps),...

Abstract We applied time‐resolved nonlinear optical techniques for investigation of carrier recombination and diffusion processes in a 420 μm thick CVD diamond, relatively free from structural point defects. Injection 10 15 –10 17 cm −3 density by two‐photon excitation monitoring absorption decay 80–800 K range provided lifetime 720 ns at T ≥ 300 K. At low temperatures, linear increase the rate with injection level was fitted an effective bimolecular coefficient B = −11 −9 3 s −1 attributed...

Time-resolved four-wave mixing has been performed in InGaN/GaN/sapphire heterostructures using picosecond pulses at 355 nm for carrier excitation. In-plane diffusion and recombination of carriers, confined the front layer 50-nm-thick InGaN, were monitored by a delayed probe beam 1064 nm. Decay times free gratings with various spatial periods allowed determination bipolar coefficient D = 2.1 cm2/s, effective lifetime 470 ps, estimate corresponding hole mobility 40 cm2/Vs density about 1018...

We report on nonequilibrium carrier dynamics in a set of hydride vapor phase epitaxy (HVPE) GaN wafers different thickness (11, 17, 41, 90, and 145 µm) grown the (0001) c-plane sapphire substrates. Carrier lifetime τR diffusion length LD were determined by picosecond transient grating free absorption (FCA) techniques. The nonradiative recombination increased from 400 ps thinnest layer up to 25 ns thickest one, varied 0.24 1.9 µm, respectively. values µm-thick HVPE are largest ones reported...

We applied time-resolved free carrier absorption (FCA) to monitor non-equilibrium dynamics in 4H epilayers and 3C SiC bulk crystals at excess densities the N = 1017 - 1019 cm-3 range. The numerical fitting of FCA decay kinetics provided linear nonlinear recombination rates 40-390 K range cross-sections eh 1064 nm. In 4H, decrease lifetime (800 ns) with excitation bimolecular Auger coefficients B=(1.2±0.4)×10-12 cm3/s C=(7±4)×10-31cm6/s, respectively, room temperature. These values for were...

Light-induced absorption and diffraction measurements of resonantly excited 10-nm-width InGaAs multiple quantum wells have been carried out, using circularly polarized beams at 1064 nm. Spin relaxation time τs≃280±15 ps has determined by monitoring dynamics light bleaching 0.04 mJ/cm2, while a nonlinearly compressed spin component in varied from 220±20 to 115±15 with excitation. The kinetics carrier grating randomized spins allowed the determination bipolar diffusion coefficient D=11.5...

A non-degenerate four-wave mixing technique has been applied to investigate carrier transport and recombination in heavily C-doped GaAs embedded a double-heterostructure. The carriers were injected into the 1 µm-thick p-GaAs layer via 50 nm-thick barrier of AlGaAs:C or InGaP:Si, using light interference pattern two picosecond laser pulses at 532 nm. dependence nonequilibrium grating decay time on period allows determination minority diffusion coefficients: D = 35 cm2/s for ( cm−3) with...

Time-resolved absorption bleaching and four-wave mixing techniques have been used for studies of spin relaxation nonequilibrium carrier dynamics in resonantly excited InGaAs/GaAs multiple quantum well structures. Kinetics at 1064 nm provided times 240–280 ps lifetimes 750–1000 low excitations. At higher excitations, nearly three-fold increase spin-relaxation rate has measured by the FWM technique, while decrease lifetime was much less pronounced. The kinetics grating with randomized spins...

Degenerate four-wave mixing experiments with 25-ps pulses at a wavelength of 1.06 µm have been performed in ZnTe crystals doped deep vanadium impurity and codoped by aluminum or scandium. Complex analysis the time resolved measurements together exposure characteristics various delay times probe beam revealed effective carrier generation from defect complexes their subsequent recombination to Zn-vacancies Al samples. On other hand, significantly faster diffusion Sc crystal disclosed build-up...

The aim of this study was to evaluate the optimal algorithm high-power pulsed light technique constructed for decontamination meat surface from pathogenic microorganisms.Our experimental data indicate that is fast and effective chicken tool can decrease food pathogens Salmonella Listeria by 2.0 orders magnitude in non-thermal conditions.The equipment obtained may serve future advanced development which could be used matrixes or related surfaces conditions.

We demonstrate a novel way to analyse carrier recombination and transport processes in photorefractive semiconductors via the exposure characteristics of light induced diffraction. The results picosecond four-wave mixing on free gratings semi-insulating GaAs crystals at various grating periods modulation depths interference pattern are discussed. role deep-trap recharging diffusion is sensitively revealed through feedback effect space-charge field non-equilibrium transport.

Photoelectric properties of 3C sublimation-grown epitaxial layers with different structural quality were studied by using time-resolved picosecond transient grating and free carrier absorption techniques. The layer was described a parameter LTW which gives the total length twin boundaries in layer. Optical measurements diffusion coefficients lifetimes wide excess density (N >1018 cm-3) temperature range (10 K to 300 K) revealed defect dependent ambipolar mobility value at RT as well...

We present a comprehensive study of photoexcited carrier dynamics in differently grown InGaN/InGaN multiple quantum well (MQW) structures, modified by insertion wide interlayer structure and subsequent growth shaped wells (rectangular, triangular, trapezoidal). This approach strain management allowed the reduction dislocation density due to gradually increasing In content shaping smooth well/barrier interfaces. A set c-oriented MQW structures emitting at 470 nm were Vilnius University,...

We demonstrate that a parametrically pumped picosecond laser has enough coherence and energy to write transient phase gratings at nonresonant interaction, thus allowing study of time-resolved carrier transport in CdTe crystals be made. Autocorrelation trace light diffraction efficiency on grating allowed us measure length the parametric generator. Carrier diffusion, recombination, drift light-created internal space-charge (SC) electric fields have been studied vanadium or germanium doped...

We present nonlinear optical four-wave mixing (FWM) and microwave absorption (MWA) techniques for the monitoring of nonequilibrium carrier dynamics in CdTe epitaxial layers grown on GaAs by either hydrogen transport (H2T) or metalorganic vapour phase epitaxy, as well a sub-surface region single crystals. For excitation, picosecond YAG parametric laser pulses were used to record free surface gratings with variable thickness excited region, while ns-YAG utilized edge excitation...

Using interdisciplinary fields relevant to a highly excited semiconductor -nonequilibrium phenomena in high density plasma, light-induced changes of optical properties, and dynamic holography, we developed time-resolved four-wave mixing technique for monitoring the spatial temporal carrier dynamics wide band-gap semiconductors.This opened new possibility analyse fast electronic processes non-destructive "all-optical" way, i.e. without any electrical contacts.This allowed evaluation...