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

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

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$p$ core-level and Mn 3$d$ valence-band spectra of the Mn/GaAs (001) sample heated to 600 $^{\circ}$C were similar to those of Ga$_{1-x}$Mn$_x$As, zinc-blende-type MnAs dots, and/or interstitial Mn in tetrahedrally coordinated by As atoms, suggesting that the Mn 3$d$ 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