23 research outputs found
Weak localization in InSb thin films heavily doped with lead
The paper reports on the investigations of the weak localization (WL) effects
in 3D polycrystalline thin films of InSb. The films are closely compensated
showing the electron concentration n>10^{16} cm^{-3} at the total concentration
of the donor and acceptor type structural defects >10^{18} cm^{-3}. Unless
Pb-doped, the InSb films do not show any measurable or show very small WL
effect at 4.2 K. The Pb-doping to the concentration of the order of 10^{18}
cm^{-3} leads to pronounced WL effects below 7 K. In particular, a clearly
manifested SO scattering is observed. From the comparison of the experimental
data on temperature dependence of the magnetoresistivity and sample resistance
with the WL theory, the temperature dependence of the phase destroying time is
determined. The determination is performed by fitting theoretical terms
obtained from Kawabata's theory to experimental data on magnetoresistance. It
is concluded that the dephasing process is connected to three separate
interaction processes. The first is due to the SO scatterings and is
characterized by temperature-independent relaxation time. The second is
associated with the electron-phonon interaction. The third dephasing process is
characterized by independent on temperature relaxation time tau_c. This
relaxation time is tentatively ascribed to inelastic scattering at extended
structural defects, like grain boundaries. The resulting time dephasing time
shows saturation in its temperature dependence. The temperature dependence of
the resistance of the InSb films can be explained by the electron-electron
interaction for T2 K.Comment: 15 pages with 5 figure
Sum-over-states vs quasiparticle pictures of coherent correlation spectroscopy of excitons in semiconductors; femtosecond analogues of multidimensional NMR
Two-dimensional correlation spectroscopy (2DCS) based on the nonlinear
optical response of excitons to sequences of ultrafast pulses, has the
potential to provide some unique insights into carrier dynamics in
semiconductors. The most prominent feature of 2DCS, cross peaks, can best be
understood using a sum-over-states picture involving the many-body eigenstates.
However, the optical response of semiconductors is usually calculated by
solving truncated equations of motion for dynamical variables, which result in
a quasiparticle picture. In this work we derive Green's function expressions
for the four wave mixing signals generated in various phase-matching directions
and use them to establish the connection between the two pictures. The formal
connection with Frenkel excitons (hard-core bosons) and vibrational excitons
(soft-core bosons) is pointed out.Comment: Accepted to Phys. Rev.
Probing Interband Coulomb Interactions in Semiconductor Nanocrystals with 2D Double-Quantum Coherence Spectroscopy
Using previously developed exciton scattering model accounting for the
interband, i.e., exciton-biexciton, Coulomb interactions in semiconductor
nanocrystals (NCs), we derive a closed set of equations for 2D double-quantum
coherence signal. The signal depends on the Liouville space pathways which
include both the interband scattering processes and the inter- and intraband
optical transitions. These processes correspond to the formation of different
cross-peaks in the 2D spectra. We further report on our numerical calculations
of the 2D signal using reduced level scheme parameterized for PbSe NCs. Two
different NC excitation regimes considered and unique spectroscopic features
associated with the interband Coulomb interactions are identified.Comment: 11 pages, 5 figure
Planar Construction of Extraordinary Magnetoresistance Sensor
A new version of the construction of the extraordinary magnetoresistance effect (EMR) based magnetic sensor has been proposed [2]. The differences between the original three dimensional (3D) construction and proposed 2D (planar) construction are presented. In proposed construction the metallic thin film (shunt) is coplanar with the semiconductor sensitive element. There are advantages of that planar construction like easier way of technological obtaining of the device. Another advantage is its application for EMR sensors based on new electronic materials like graphene and topological insulator thin films. The validity of the planar construction has been experimentally confirmed for model EMR sensors based on InSb/Ag structures. Comparison of the obtained experimental data with computational simulations of the EMR effect on planar model EMR sensors is performed Finite element method (FEM) is used as a tool for obtaining EMR effect simulations
O możliwości zastosowania wysokotemperaturowych czujników Halla opartych o InSb w diagnostyce magnetycznej tokamaka ITER
We report on irradiation experiments of InSb-based Hall samples at two types of neutron spectrums. One with thermal neutrons (natural neutron spectrum of fission reactor) and second with fast neutrons (filtered spectrum). Fluences in both cases reached almost 1018 cm-2 and that led to significant decreasing of electron mobility of samples. In case of thermal neutrons, transmutation process led to increasing of electron concentration of about 2.3×1018 cm-3. For samples irradiated with fast neutrons, twofold effect was observed: increase in electron concentration for samples with low carrier density and decrease in electron concentration for samples with high carrier density. All results raise important issue, that in case of ITER ex-vessel steady state sensors, research at different spectrum of neutrons are necessary.W artykule przedstawione zostały wyniki badań nad napromieniowaniem neutronami struktur halotronowych bazujących na antymonku indu (InSb). Część próbek została napromieniowana w strumieniu neutronów termicznych (widmo naturalne neutronów reaktora MARIA w Świerku), a pozostałe próbki w strumieniu neutronów prędkich (widmo filtrowane neutronów reaktora). W obu przypadkach dozy neutronów były zbliżone do poziomu 1018 cm-2, doprowadzając do znacznego spadku ruchliwości elektronów w cienkich warstwach InSb. W przypadku napromieniowania neutronami termicznymi zaobserwowano wzrost koncentracji elektronów o wartość ok. 2,3×1018 cm-3, głównie za sprawą transmutacji In -> Sn. Dla próbek napromieniowanych neutronami prędkimi wystąpiły dwa przeciwne efekty: wzrost koncentracji elektronów dla próbek o niskiej początkowej koncentracji elektronów, oraz spadek koncentracji dla próbek o wysokiej początkowej koncentracji elektronów. Wyniki badań wskazują, że w przypadku zastosowania czujników Halla w tokamaku ITER niezbędne jest przeprowadzenie badań w strumieniach neutronów o różnym widmie energetycznym
Determination of Niobium(V) and Tantalum(V) as 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (Br-PADAP)-citrate ternary complexes in geological materials using ion-interaction reversed-phase high-performance liquid chromatography
AFM and electron microscopy study of the unusual aggregation behavior of metallosurfactants based on iron(II) complexes with bipyridine ligands
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