458 research outputs found
Interaction between Mn Ions and Free Carriers in Quantum Wells with Asymmetrical Semimagnetic Barriers
Investigations of photoluminescence (PL) in the magnetic field of quantum
structures based on the ZnSe quantum well with asymmetrical ZnBeMnSe and ZnBeSe
barriers reveal that the introduction of Be into semimagnetic ZnMnSe causes a
decrease of the exchange integrals for conductive and valence bands as well as
the forming of a complex based on Mn, degeneration of an energy level of which
with the energy levels of the V band of ZnBeMnSe or ZnSe results in spin-flip
electron transitions.Comment: Accepted to Europhys. Let
Plasma probe characteristics in low density hydrogen pulsed plasmas
Probe theories are only applicable in the regime where the probe's
perturbation of the plasma can be neglected. However, it is not always possible
to know, a priori, that a particular probe theory can be successfully applied,
especially in low density plasmas. This is especially difficult in the case of
transient, low density plasmas. Here, we applied probe diagnostics in
combination with a 2D particle-in-cell model, to an experiment with a pulsed
low density hydrogen plasma. The calculations took into account the full
chamber geometry, including the plasma probe as an electrode in the chamber. It
was found that the simulations reproduce the time evolution of the probe IV
characteristics with good accuracy. The disagreement between the simulated and
probe measured plasma density is attributed to the limited applicability of
probe theory to measurements of low density pulsed plasmas. Indeed, in the case
studied here, probe measurements would lead to a large overestimate of the
plasma density. In contrast, the simulations of the plasma evolution and the
probe characteristics do not suffer from such strict applicability limits.
These studies show that probe theory cannot be justified through probe
measurements
Numerical and experimental studies of the carbon etching in EUV-induced plasma
We have used a combination of numerical modeling and experiments to study
carbon etching in the presence of a hydrogen plasma. We model the evolution of
a low density EUV-induced plasma during and after the EUV pulse to obtain the
energy resolved ion fluxes from the plasma to the surface. By relating the
computed ion fluxes to the experimentally observed etching rate at various
pressures and ion energies, we show that at low pressure and energy, carbon
etching is due to chemical sputtering, while at high pressure and energy a
reactive ion etching process is likely to dominate
Room-temperature near-infrared silicon carbide nanocrystalline emitters based on optically aligned spin defects
Bulk silicon carbide (SiC) is a very promising material system for
bio-applications and quantum sensing. However, its optical activity lies beyond
the near infrared spectral window for in-vivo imaging and fiber communications
due to a large forbidden energy gap. Here, we report the fabrication of SiC
nanocrystals and isolation of different nanocrystal fractions ranged from 600
nm down to 60 nm in size. The structural analysis reveals further fragmentation
of the smallest nanocrystals into ca. 10-nm-size clusters of high crystalline
quality, separated by amorphization areas. We use neutron irradiation to create
silicon vacancies, demonstrating near infrared photoluminescence. Finally, we
detect, for the first time, room-temperature spin resonances of these silicon
vacancies hosted in SiC nanocrystals. This opens intriguing perspectives to use
them not only as in-vivo luminescent markers, but also as magnetic field and
temperature sensors, allowing for monitoring various physical, chemical and
biological processes.Comment: 5 pages, 4 figure
International Scientific Conference «From Ancient Russia to the Russian Federation: History of the Russian Statehood»
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