Temperature Dependence of the Band-Edge Injection Electroluminescence of 3C-SiC pn Structure

2007 ◽  
Vol 556-557 ◽  
pp. 427-430 ◽  
Author(s):  
Anatoly M. Strel'chuk ◽  
Alexander A. Lebedev ◽  
N.S. Savkina ◽  
Alexey N. Kuznetsov
Keyword(s):  
Activation Energy ◽  
Emission Band ◽  
Room Temperature ◽  
Free Exciton ◽  
Charge Carriers ◽  
Full Width ◽  
Half Maximum ◽  
Exciton Annihilation ◽  
Increasing Temperature ◽  
Injection Electroluminescence

We present the injection electroluminescence spectra in the temperature range 290-760 K of 3C-SiC pn structure, which was fabricated by sublimation epitaxy in vacuum on 6H-SiC substrate. The dominant emission band of injection electroluminescence (IEL) spectrum was observed in the green region; at room temperature the IEL intensity outside the region of hν ≈ 2.0- 2.5 eV was less than 3% of that of the green peak. The peak parameters at room temperature are: hνmax ≈ 2.32 eV, full width at half maximum w ≈ 100 meV. The green peak shifted in the longwave direction with increasing temperature; the hνmax (T) dependence was linear with the slope of - 1.3x10-4 eV/K. Both the IEL intensity of the green peak at hνmax and band width w increased upon heating. The w(T) dependence was linear with the slope of 4.6x10-4 eV/K; intensity increased with the activation energy of 70 meV. The green IEL band can be considered to be due to the free exciton annihilation or to the band-band recombination and edge IEL increasing with rising temperature can be explained by the nonequilibrium charge carriers lifetime increasing.

Temperature Dependence of the Band-Edge Injection Electroluminescence of 4H-SiC pn Structure

2013 ◽  
Vol 740-742 ◽  
pp. 569-572 ◽  
Author(s):  
Anatoly M. Strel'chuk ◽  
Evgenia V. Kalinina ◽  
Alexander A. Lebedev
Keyword(s):  
Room Temperature ◽  
Charge Carriers ◽  
Band Edge ◽  
Near Band Edge ◽  
Full Width ◽  
Wave Direction ◽  
Green Band ◽  
Long Wave ◽  
Increasing Temperature ◽  
Injection Electroluminescence

We present the injection electroluminescence spectra in the temperature range 290-800 K of 4H-SiC pn structure, which was formed by implantation of Al+ ions in low-doped n-type conductivity 4H-SiC epitaxial layer. The dominant emission band of injection electroluminescence (IEL) spectrum at room temperature was observed in the blue-green region; as the temperature is raised, the blue-green band is quenched, while UV band (near band-edge) IEL become dominant. The peak parameters of UV band at room temperature are: hmax  3.17 eV, full width at half maximum w  90 meV. The UV peak shifted in the long-wave direction with increasing temperature; the hmax (T) dependence was linear with the slope of -2.3∙10-4 eV/K. Both the IEL intensity of the UV peak at hmax and band width w increased upon heating. The w(T) dependence was linear with the slope of 2.9∙10-4 eV/K; intensity increased with the activation energy of 100-150 meV. The UV IEL band can be considered more probable to the band-band recombination and edge IEL increasing with rising temperature can be explained by the nonequilibrium charge carriers lifetime increasing.

Photoluminescence of Erbium-Diffused Silicon

1996 ◽  
Vol 422 ◽  
Author(s):  
H. Horiguchi ◽  
T. Kinone ◽  
R. Saito ◽  
T. Kimura ◽  
T. Ikoma
Keyword(s):  
Room Temperature ◽  
Crystalline Silicon ◽  
Luminescence Spectra ◽  
Main Peak ◽  
Silicon Substrates ◽  
Annealing Atmosphere ◽  
Full Width ◽  
Half Maximum ◽  
Strong Luminescence ◽  
Fine Structures

AbstractErbium films are evaporated on crystalline silicon substrates and are thermally diffused into silicon in an Ar+02 or H2 flow. Very sharp Er3+-related luminescence peaks are observed around 1.54 μ m.The main peak as well as the fine structures of the luminescence spectra depend on the annealing atmosphere, suggesting different luminescence centers. The full width at half maximum (FWHM) of the main peaks is ≤ 0.5nm at 20K. Thermal diffusion with Al films on top of the Er films is found to increase the intensity of the Er3+-related peaks greatly. The temperature dependence between 20 K and room temperature is relatively small, and a strong luminescence is obtained at room temperature.

scholarly journals Observation of strong excitonic magneto-chiral anisotropy in twisted bilayer van der Waals crystals

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Shoufeng Lan ◽  
Xiaoze Liu ◽  
Siqi Wang ◽  
Hanyu Zhu ◽  
Yawen Liu ◽  
...  
Keyword(s):  
Time Reversal ◽  
Room Temperature ◽  
Photochemical Reactions ◽  
Full Width ◽  
Half Maximum ◽  
A Value ◽  
Device Applications ◽  
Spectral Splitting ◽  
Iron Garnet ◽  
Spontaneous Magnetic Moment

AbstractThe interplay between chirality and magnetism generates a distinct physical process, the magneto-chiral effect, which enables one to develop functionalities that cannot be achieved solely by any of the two. Such a process is universal with the breaking of parity-inversion and time-reversal symmetry simultaneously. However, the magneto-chiral effect observed so far is weak when the matter responds to photons, electrons, or phonons. Here we report the first observation of strong magneto-chiral response to excitons in a twisted bilayer tungsten disulfide with the amplitude of excitonic magneto-chiral (ExMCh) anisotropy reaches a value of ~4%. We further found the ExMCh anisotropy features with a spectral splitting of ~7 nm, precisely the full-width at half maximum of the excitonic chirality spectrum. Without an externally applied strong magnetic field, the observed ExMCh effect with a spontaneous magnetic moment from the ferromagnetic substrate of thulium iron garnet at room temperature is favorable for device applications. The unique ExMCh processes provide a new pathway to actively control magneto-chiral applications in photochemical reactions, asymmetric synthesis, and drug delivery.

scholarly journals Observation of strong excitonic magneto-chiral anisotropy in twisted bilayer van der Waals crystals

2020 ◽  
Author(s):  
Shoufeng Lan ◽  
Xiaoze Liu ◽  
Siqi Wang ◽  
Hanyu Zhu ◽  
Yawen Liu ◽  
...  
Keyword(s):  
Time Reversal ◽  
Room Temperature ◽  
Photochemical Reactions ◽  
Full Width ◽  
Half Maximum ◽  
A Value ◽  
Device Applications ◽  
Spectral Splitting ◽  
Iron Garnet ◽  
Spontaneous Magnetic Moment

Abstract The interplay between chirality and magnetism generates a distinct physical process, the magneto-chiral effect, which enables one to develop functionalities that cannot be achieved solely by any of the two. Such a process is universal with the breaking of parity-inversion and time-reversal symmetry simultaneously. However, the magneto-chiral effect observed so far is weak when the matter responds to photons, electrons, or phonons. Here we report the first observation of strong magneto-chiral response to excitons in a twisted bilayer tungsten disulfide with the amplitude of excitonic magneto-chiral (ExMCh) anisotropy reaches a value of ~4%. We further found the ExMCh anisotropy features with a spectral splitting of ~7 nm, precisely the full-width at half maximum of the excitonic chirality spectrum. Without an externally applied strong magnetic field, the observed ExMCh effect with a spontaneous magnetic moment from the ferromagnetic substrate of thulium iron garnet at room temperature is favorable for device applications. The unique ExMCh processes provide a new pathway to actively control magneto-chiral applications in photochemical reactions, asymmetric synthesis, and drug delivery.

NOVEL BLUE ORGANIC LIGHT-EMITTING MATERIAL

2004 ◽  
Vol 13 (03n04) ◽  
pp. 649-653 ◽  
Author(s):  
YUN-HI KIM ◽  
HYUNG-SUN KIM ◽  
JUN-HWAN AHN ◽  
SUNG-HAN KIM ◽  
SOON-KI KWON
Keyword(s):  
Emission Band ◽  
Blue Emission ◽  
Luminous Efficiency ◽  
Full Width ◽  
Half Maximum ◽  
Device Structure ◽  
Light Emitting ◽  
Organic Light ◽  
Chromaticity Coordinates ◽  
Narrow Emission

The blue light-emitting material was synthesized. With the non-doped, blue-emitting material in the multilayer device structure, it was possible to achieve the luminous efficiency of 3.38 cd/A at 110 mA/cm2. The EL spectrum of the ITO / CuPc / NPB / BDPSP / Alq 3/ Mg : Ag device showed a narrow emission band with full width at half maximum (FWHM) 70 nm and λ max =448.25 nm . The emitting color of the device showed the highly pure blue emission (x,y)=(0.158, 0.10) for ITO / CuPc / NPB / BDPSP / Alq 3/ Mg : Ag in CIE (Commission Internationale de l'Eclairage) chromaticity coordinates.

6H(n+)/3C(n)/6H(p+) - SiC Structures Grown by Sublimation Epitaxy

2005 ◽  
Vol 108-109 ◽  
pp. 713-716 ◽  
Author(s):  
Anatoly M. Strel'chuk ◽  
Alexander A. Lebedev ◽  
A.E. Cherenkov ◽  
Alexey N. Kuznetsov ◽  
Alla S. Tregubova ◽  
...  
Keyword(s):  
Quantum Well ◽  
Free Exciton ◽  
High Current ◽  
Excess Current ◽  
Forward Current ◽  
Current Voltage ◽  
Barrier Type ◽  
Current Voltage Characteristics ◽  
Exciton Annihilation ◽  
Injection Electroluminescence

Investigation of the multilayer 6H(n+)/3C(n)/6H(p+)-SiC heterostructure grown by sublimation epitaxy show that the injection electroluminescence (IEL) in the green region (hνmax≈2.30-2.35eV) of spectrum is dominant. This band is close to the electroluminescence peak due to defects in 6H-SiC but also can be due to free exciton annihilation in a quantum well in 3C-SiC at the 6H/3C-SiC heterointerface. At high current the IEL peak at hνmax≈2.9 eV is found. This peak (and also two another peaks in blue part of spectra: hνmax≈2.6 eV and hνmax≈2.72 eV) can be attributed to recombination in 6H-SiC. The forward current-voltage characteristics for best structures are close to those for ideal 6H-SiC pn homostructure and characterized by abrupt breakdown. A lot of structures are characterized by barrier type excess current. Structure in the region of evident 3C-SiC inclusion is characterized by high forward and reverse excess currents.

CBE Growth of InP with Triethylindium and Metalorganic Phosphorous Precursors: Bisphosphinoethane and Tertiarybutyl-Phosphine

1992 ◽  
Vol 282 ◽  
Author(s):  
Albert Chin ◽  
Steve Hersee ◽  
Paul Martin ◽  
John Mazurowski ◽  
James Ballingall ◽  
...  
Keyword(s):  
Indium Phosphide ◽  
Room Temperature ◽  
Epitaxial Layers ◽  
Full Width ◽  
Half Maximum ◽  
Substrate Interface ◽  
Sims Analysis

ABSTRACTTwo metallorganic phosphorous precursors, bisphosphinoethane (BPE) and tertiarybutyl phosphine (TBP), were studied. For indium phosphide (InP) grown using BPE, the measured room temperature and 77K Hall mobilities were 4,200 and 22,000 cm2/Vs, with carrierdensities 5.7E15 and 4.0E15 cm−3, respectively. For InP grown using TBP, the measured room temperature and 77K Hall mobilities were 4,400 and 26,000 cm2/Vs, with carrier densities 6.4E15 and 5.1E15 cm−3, respectively. An impurity build-up at the substrate interface is responsible for the relatively low mobility in the adjacent epitaxial layers. SIMS analysis showed that S and Si are the primary impurities measured in films grown with BPE and TBP, respectively; impurity concentrations increasedwith cracking temperature. The full width at half maximum (FWHM) of donor bound exciton peaks measured by 2.2K photoluminescence for InP grown by BPE and TBP were 0.84 and 1.28 meV, respectively.

Decomposition kinetics of cobalt complexes of phenoxy radicals studied by EPR method

1980 ◽  
Vol 45 (2) ◽  
pp. 464-474 ◽  
Author(s):  
Ladislav Omelka ◽  
Alexander Tkáč
Keyword(s):  
Activation Energy ◽  
Room Temperature ◽  
Effective Activation Energy ◽  
Decomposition Kinetics ◽  
Peroxy Radicals ◽  
Substitution Reactions ◽  
Phenoxy Radicals ◽  
Increasing Temperature ◽  
Kinetics Of ◽  
Homolytic Substitution

In bimolecular homolytic substitution reactions type SH2 between coordinated peroxy radicals [Co(III)]RO2 and partially hindered bisphenol 4,4'-thiobis-(3-methyl-6-tert-butylphenol) (an antioxidant with commercial name Santonox R) in non-polar medium at room temperature an equilibrium is established between free and Co(III)-coordinated phenoxy radicals. Increasing temperature shifts the equilibrium in favour of the decomplexed free radicals. The complexation-decomplexation process of phenoxy radicals is practically reversible up to 90°C. Polar coordinating solvents (methanol, H2O, diethyl ether, tetrahydrofurane) displace irreversibly the radicals from the complexes. From their decomposition kinetics at various temperatures activation energy of decomplexation by methanol has been determined (110 ± 8 kJ mol-1). The displaced free partially hindered phenoxy radicals are not sufficiently stable and undergo subsequent radical transformations (dimerization, intramolecular and intermolecular H-transfer) with effective activation energy about 67 kJ mol-1.

Semiconducting Molybdenum Pyrochlores for high Temperature Applications

1998 ◽  
Vol 512 ◽  
Author(s):  
V. Ponnambalam ◽  
U. V. Varadaraju
Keyword(s):  
Activation Energy ◽  
Electrical Resistivity ◽  
High Temperature ◽  
Low Temperature ◽  
Solid Solutions ◽  
Power Factor ◽  
Charge Carriers ◽  
Temperature Range ◽  
Maximum Power Factor ◽  
Increasing Temperature

ABSTRACTThe solid solutions (Y1-xYbx)2Mo2O7 were prepared and the systematic changes in the electrical resistivity (ρ=l/σ), thermopower (S) and power factor (S2σ) have been studied in the temperature range 300–900 K. The lattice parameters ‘a’ and ‘c’ are smaller for higher Yb3+ content phases due to smaller Yb3+ radius and a small tetragonality is observed for all the phases. Semiconducting behaviour is seen for all compositions with systematic increase in activation energy with increasing Yb content. All compositions show negative thermopower indicating electrons are the majority charge carriers in the temperature range of measurements. The calculated power factor values S2σ increase with increasing temperature in the low temperature region and a maximum power factor of ∼0.76×10−7 Wcm−1K−2 is observed at 650K.

Features of the Band-Edge Injection Electroluminescence in 4H-SiC pn Structures

2015 ◽  
Vol 821-823 ◽  
pp. 289-292
Author(s):  
Anatoly M. Strel'chuk ◽  
Yury S. Kuz’michev ◽  
Konstantin F. Shtel’makh
Keyword(s):  
Activation Energy ◽  
Irradiation Temperature ◽  
Band Edge ◽  
Fundamental Feature ◽  
Wide Range ◽  
Current Densities ◽  
Increasing Temperature ◽  
First Time ◽  
Injection Electroluminescence ◽  
Nonequilibrium Carriers

Band-edge (hνmax=3.17-3.18 eV at T=293 K) injection electroluminescence (IEL) characteristics of 4H-SiC pn structures as a function of doping, electron irradiation, temperature, and current are presented. The intensity of the UV band increases with temperature in the range 290-800 K (with an activation energy Ea of about 90 meV), which is observed for the first time in a wide range of current densities from 9 A/cm2 up to 2∙104 A/cm2. This effect is a fundamental feature of the band-edge IEL in SiC pn structures. The dependence of the intensity L on the current is of the power-law type, L~Jm; at high currents m≈1 at T=650-800 K. This result is probably the first direct observation of the diffusion current in SiC pn structures. The rise in the intensity of the band-edge IEL with increasing temperature and its decrease upon irradiation are probably due to the corresponding change in the lifetime of nonequilibrium carriers.

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