Photoelectrical Parameters of a PVT Grown Bulk 15R-SiC Crystal at Different Stages of Growth

2015 ◽  
Vol 821-823 ◽  
pp. 253-256
Author(s):  
Gediminas Liaugaudas ◽  
Donatas Dargis ◽  
Kęstutis Jarašiūnas ◽  
Nikolaos Tsavdaris ◽  
Eirini Sarigiannidou ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Crystal Growth ◽  
Room Temperature ◽  
Vapour Transport ◽  
Optical Pump ◽  
Time Resolved ◽  
Pump Probe ◽  
Trap Concentration ◽  
Stages Of Growth

The electronic quality of a Physical Vapour Transport (PVT) grown 15R-SiC crystal at different stages of growth was assessed by time-resolved optical pump-probe techniques. The measured differential transmittivity (DT) kinetics for the layers corresponding to the initial, middle and final stages of growth revealed clear differences in the decay of the DT signal, indicating a decreasing concentration of traps at the later stages of the crystal growth. The estimated trap concentration in the initial layer wasNT≈ 1019cm-3, while it decreased down to less than 2×1018cm-3in the top layer. The injection dependence of the diffusion coefficient at room temperature confirmed the gradual decrease ofNTin the layers corresponding to later stages of growth. Accordingly, the bipolar diffusion coefficient in the middle and the top layer wasDa≈ 2 cm2/s, whileDa= 0.9 cm2/s was measured in the layer closest to the seed.

Pump-Probe Measurements Using Silicon Nanocrystal Waveguides

2003 ◽  
Vol 770 ◽  
Author(s):  
Nathanael Smith ◽  
Max J. Lederer ◽  
Marek Samoc ◽  
Barry Luther-Davies ◽  
Robert G. Elliman
Keyword(s):  
Probe Beam ◽  
Time Resolution ◽  
Pump Beam ◽  
Silicon Nanocrystals ◽  
Continuous Wave ◽  
Optical Gain ◽  
Optical Pump ◽  
Time Resolved ◽  
Pump Probe ◽  
Probe Measurements

AbstractOptical pump-probe measurements were performed on planar slab waveguides containing silicon nanocrystals in an attempt to measure optical gain from photo-excited silicon nanocrystals. Two experiments were performed, one with a continuous-wave probe beam and a pulsed pump beam, giving a time resolution of approximately 25 ns, and the other with a pulsed pump and probe beam, giving a time resolution of approximately 10 ps. In both cases the intensity of the probe beam was found to be attenuated by the pump beam, with the attenuation increasing monotonically with increasing pump power. Time-resolved measurements using the first experimental arrangement showed that the probe signal recovered its initial intensity on a time scale of 45-70 μs, a value comparable to the exciton lifetime in Si nanocrystals. These data are shown to be consistent with an induced absorption process such as confined carrier absorption. No evidence for optical gain was observed.

scholarly journals Time-resolved x-ray/optical pump-probe simulations on N2 molecules

2019 ◽  
Vol 6 (2) ◽  
pp. 024101
Author(s):  
Athiya Mahmud Hanna ◽  
Oriol Vendrell ◽  
Robin Santra
Keyword(s):  
Optical Pump ◽  
Time Resolved ◽  
Pump Probe ◽  
X Ray

scholarly journals Unambiguous determination of spin dephasing times in ZnO by time-resolved magneto-optical pump-probe experiments

2014 ◽  
Vol 251 (9) ◽  
pp. 1861-1871 ◽  
Author(s):  
Sebastian Kuhlen ◽  
Ralph Ledesch ◽  
Robin de Winter ◽  
Matthias Althammer ◽  
Sebastian T. B. Gönnenwein ◽  
...  
Keyword(s):  
Optical Pump ◽  
Time Resolved ◽  
Pump Probe ◽  
Spin Dephasing ◽  
Unambiguous Determination

scholarly journals Pump-Probe Time-Resolved Serial Femtosecond Crystallography at SACLA: Current Status and Data Collection Strategies

2019 ◽  
Vol 9 (24) ◽  
pp. 5505 ◽  
Author(s):  
Eriko Nango ◽  
Minoru Kubo ◽  
Kensuke Tono ◽  
So Iwata
Keyword(s):  
Data Collection ◽  
Free Electron ◽  
Free Electron Laser ◽  
Current Status ◽  
Optical Pump ◽  
Time Resolved ◽  
Pump Probe ◽  
X Ray ◽  
Collection Strategies ◽  
Serial Femtosecond Crystallography

Structural information on protein dynamics is a critical factor in fully understanding the protein functions. Pump-probe time-resolved serial femtosecond crystallography (TR-SFX) is a recently established technique for visualizing the structural changes or reactions in proteins that are at work with high spatial and temporal resolution. In the pump-probe method, protein microcrystals are continuously delivered from an injector and exposed to an X-ray free-electron laser (XFEL) pulse after a trigger to initiate a reaction, such as light, chemicals, temperature, and electric field, which affords the structural snapshots of intermediates that occur in the protein. We are in the process of developing the device and techniques for pump-probe TR-SFX while using XFEL produced at SPring-8 Angstrom Compact Free-Electron Laser (SACLA). In this paper, we described our current development details and data collection strategies for the optical pump X-ray probe TR-SFX experiment at SACLA and then reported the techniques of in crystallo TR spectroscopy, which is useful in clarifying the nature of reaction that takes place in crystals in advance.

Optical Characterization of p-Type 4H-SiC Epilayers

2015 ◽  
Vol 821-823 ◽  
pp. 249-252 ◽  
Author(s):  
Gediminas Liaugaudas ◽  
Donatas Dargis ◽  
Pawel Kwasnicki ◽  
Hervé Peyre ◽  
Roxana Arvinte ◽  
...  
Keyword(s):  
Carrier Lifetime ◽  
Diffusion Length ◽  
Hole Mobility ◽  
Optical Characterization ◽  
Optical Pump ◽  
Time Resolved ◽  
Pump Probe ◽  
Activation Ratio ◽  
P Type

A series of aluminium doped (from 2×1016to 8×1019cm-3) 4H-SiC epitaxial layers were mainly studied by Low Temperature Photoluminescence and time-resolved optical pump-probe techniques to determine the concentration of aluminium, its activation ratio, the doping related carrier lifetime, hole mobility and excess carrier diffusion length.

scholarly journals Time-resolved polarimetry for photoexcited QP dynamics in Bi2212

2015 ◽  
Vol 29 (25n26) ◽  
pp. 1542031
Author(s):  
K. Watanabe ◽  
S. Tsuchiya ◽  
Y. Toda ◽  
T. Kurosawa ◽  
M. Oda ◽  
...  
Keyword(s):  
High Temperature ◽  
Symmetry Breaking ◽  
Probe Beam ◽  
Pump Beam ◽  
High Temperature Superconductor ◽  
Beam Polarization ◽  
Optical Pump ◽  
Quasi Particle ◽  
Time Resolved ◽  
Pump Probe

The dynamics of quasi-particle (QP) excitations with different symmetry is investigated in the superconducting (SC) and pseudogap (PG) states of the high-temperature superconductor [Formula: see text] (Bi2212) using a polarization-sensitive optical pump-probe measurement. The observation of distinct anisotropies for SC excitations and for PG excitations by the probe beam polarization and absence of any dependence on the pump beam polarization evidence the existence of a spontaneous spatial symmetry breaking in the PG state.

The Early Stages of Growth in Gold Microcrystals

1967 ◽  
Vol 25 ◽  
pp. 344-345
Author(s):  
R. G. Peacock ◽  
R. H. Morriss
Keyword(s):  
Crystal Growth ◽  
Growth Medium ◽  
Growth Process ◽  
Room Temperature ◽  
Electron Diffraction Study ◽  
Gold Concentration ◽  
Electron Microscopic ◽  
Stages Of Growth ◽  
Early Stages ◽  
Gold Microcrystals

Thin crystals of colloidal gold exhibiting trigonal symmetry can be grown from solution by the reduction of chlorauric acid with salicylic acid. At room temperature the complete growth process requires approximately 240 hours, and the resulting crystals are about 100 Å in thickness and several microns in width. This system particularly lends itself to an electron microscopic and electron diffraction study of the nucleation and early stages of crystal growth. With this objective in mind samples were extracted from the growth medium at periodic intervals throughout the growth process and examined in the electron microscope. In order to examine the crystals at various stages of development as they actually exist in the growth medium, it was necessary to dilute the extracted samples several thousand to one with distilled water. Since this form of crystal growth is dependent on the gold concentration in the solution, dilution seems to be the most efficient way of halting growth without disturbing the crystal.

Optically Induced Sub-Wavelength Transient Apertures in Sb-Te Based Films

2011 ◽  
Vol 1338 ◽  
Author(s):  
Robert E. Simpson ◽  
Paul J. Fons ◽  
Alexander V. Kolobov ◽  
Xiomin Wang ◽  
Junji Tominaga
Keyword(s):  
Thin Films ◽  
Density Functional ◽  
Near Field ◽  
Diffraction Limit ◽  
Optical Pump ◽  
Time Resolved ◽  
Pump Probe ◽  
Thermally Induced ◽  
Melting Temperatures ◽  
Sub Wavelength

ABSTRACTThe origin of sub-diffraction-limit apertures in Sb-based thin films is discussed. Electromagnetic energy can be channeled by these apertures thus allowing near-field focussing- the Super-RENS effect. The aperture formation within Sb, Sb2Te3, Sb2Te, SbTe and Ge2Sb2Te5 is investigated by time resolved optical pump-probe techniques and found to occur without melting. Density functional calculations have shown that these materials exhibit a thresholdlike change in their optical properties below their melting temperatures. The threshold is shown to be a consequence of thermally induced misalignment of p-orbital bonds. It is the non-linearity of this process that leads to the formation of the sub-diffraction-limit apertures.

RECENT ADVANCES IN ULTRAFAST TIME-RESOLVED SCANNING TUNNELING MICROSCOPY

2018 ◽  
Vol 25 (Supp01) ◽  
pp. 1841003 ◽  
Author(s):  
YE TIAN ◽  
FAN YANG ◽  
CHAOYU GUO ◽  
YING JIANG
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Spatial Resolution ◽  
Temporal Resolution ◽  
Near Infrared ◽  
Atomic Scale ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Optical Pump ◽  
Time Resolved ◽  
Pump Probe

Making smaller and faster functional devices has led to an increasing demand for a microscopic technique that allows the investigation of carrier and phonon dynamics with both high spatial and temporal resolutions. Traditional optical pump–probe methods can achieve femtosecond temporal resolution but fall short in the spatial resolution due to the diffraction limit. Scanning tunneling microscopy (STM), on the contrary, has realized atomic-scale spatial resolution relying on the high sensitivity of the tunneling current to the tip-sample distance. However, limited by the electronics bandwidth, STM can only push the temporal resolution to the microseconds scale, restricting its applications to probe various ultrafast dynamic processes. The combination of these two methods takes advantages of optical pump–probe techniques and highly localized tunneling currents of STM, providing one viable solution to track atomic-scale ultrafast dynamics in single molecules and low-dimensional materials. In this review, we will focus on several ultrafast time-resolved STM methods by coupling the tunneling junctions with pulsed electric waves, THz, near-infrared and visible laser. Their applications to probe the carrier dynamics, spin dynamics, and molecular motion will be highlighted. In the end, we will present an outlook on the challenges and new opportunities in this field.

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