36,819 research outputs found
Monolithic arrays of surface emitting laser NOR logic devices
Monolithic, cascadable, laser-logic-device arrays have been realized and characterized. The monolithic surface-emitting laser logic (SELL) device consists of an AlGaAs superlattice lasing around 780 nm connected to a heterojunction phototransistor (HPT) in parallel and a resistor in series. Arrays up to 8×8 have been fabricated, and 2×2 arrays show uniform characteristics. The optical logic output is switched off with 40 μW incident optical input
Shuttle-promoted nano-mechanical current switch
We investigate electron shuttling in three-terminal nanoelectromechanocal
device built on a movable metallic rod oscillating between two drains. The
device shows a double-well shaped electromechanical potential tunable by a
source-drain bias voltage. Four stationary regimes controllable by the bias are
found for this device: (i) single stable fixed point, (ii) two stable fixed
points, (iii) two limiting cycles, and (iv) single limiting cycle. In the
presence of perpendicular magnetic field the Lorentz force makes possible
switching from one electromechanical state to another. The mechanism of tunable
transitions between various stable regimes based on the interplay between
voltage controlled electromechanical instability and magnetically controlled
switching is suggested. The switching phenomenon is implemented for achieving
both a reliable \emph{active} current switch and sensoring of small variations
of magnetic field.Comment: 11 pages, 4 figure
Monolithic arrays of surface emitting laser NOR logic devices
Monolithic, cascadable, laser-logic-device arrays have been realized and characterized. The monolithic surface-emitting laser logic (SELL) device consists of an AlGaAs superlattice lasing around 780 nm connected to a heterojunction phototransistor (HPT) in parallel and a resistor in series. Arrays up to 8×8 have been fabricated, and 2×2 arrays show uniform characteristics. The optical logic output is switched off with 40 μW incident optical input
Self-sustained oscillations in nanoelectromechanical systems induced by Kondo resonance
We investigate instability and dynamical properties of nanoelectromechanical
systems represented by a single-electron device containing movable quantum dot
attached to a vibrating cantilever via asymmetric tunnel contact. The Kondo
resonance in electron tunneling between source and shuttle facilitates
self-sustained oscillations originated from strong coupling of mechanical and
electronic/spin degrees of freedom. We analyze stability diagram for
two-channel Kondo shuttling regime due to limitations given by the
electromotive force acting on a moving shuttle and find that the saturation
amplitude of oscillation is associated with the retardation effect of
Kondo-cloud. The results shed light on possible ways of experimental
realization of dynamical probe for the Kondo-cloud by using high tunability of
mechanical dissipation as well as supersensitive detection of mechanical
displacement
Depth profile photoemission study of thermally diffused Mn/GaAs (001) interfaces
We have performed a depth profile study of thermally diffused Mn/GaAs (001)
interfaces using photoemission spectroscopy combined with Ar-ion
sputtering. We found that Mn ion was thermally diffused into the deep region of
the GaAs substrate and completely reacted with GaAs. In the deep region, the Mn
2 core-level and Mn 3 valence-band spectra of the Mn/GaAs (001) sample
heated to 600 C were similar to those of GaMnAs,
zinc-blende-type MnAs dots, and/or interstitial Mn in tetrahedrally coordinated
by As atoms, suggesting that the Mn 3 states were essentially localized but
were hybridized with the electronic states of the host GaAs. Ferromagnetism was
observed in the dilute Mn phase.Comment: 5 pages, 4 figure
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