9 research outputs found
Thermionic Emission as a tool to study transport in undoped nFinFETs
Thermally activated sub-threshold transport has been investigated in undoped
triple gate MOSFETs. The evolution of the barrier height and of the active
cross-section area of the channel as a function of gate voltage has been
determined. The results of our experiments and of the Tight Binding simulations
we have developed are both in good agreement with previous analytical
calculations, confirming the validity of thermionic approach to investigate
transport in FETs. This method provides an important tool for the improvement
of devices characteristics.Comment: 3 pages, 3 figure, 1 tabl
Circuit-theoretic phenomenological model of an electrostatic gate-controlled bi-SQUID
A numerical model based on a lumped circuit element approximation for a
bi-superconducting quantum interference device (bi-SQUID) operating in the
presence of an external magnetic field is presented in this paper. Included in
the model is the novel ability to capture the resultant behaviour of the device
when a strong electric field is applied to its Josephson junctions by utilising
gate electrodes. The model is used to simulate an all-metallic SNS (Al-Cu-Al)
bi-SQUID, where good agreement is observed between the simulated results and
the experimental data. The results discussed in this work suggest that the
primary consequences of the superconducting field effect induced by the gating
of the Josephson junctions are accounted for in our minimal model; namely, the
suppression of the junctions super-current. Although based on a simplified
model, our results can potentially help with the task of clarifying the
microscopic origin of this effect. Also, the possible applications of this
effect regarding the operation of SQUIDs as ultra-high precision sensors, where
the performance of such devices can be improved via careful tuning of the
applied gate voltages, are discussed at the end of the paper.Comment: 9 pages, 4 figure
Manifestation of the coupling phase in microwave cavity magnonics
The interaction between microwave photons and magnons is well understood and
originates from the Zeeman coupling between spins and a magnetic field.
Interestingly, the magnon/photon interaction is accompanied by a phase factor
which can usually be neglected. However, under the rotating wave approximation,
if two magnon modes simultaneously couple with two cavity resonances, this
phase cannot be ignored as it changes the physics of the system. We consider
two such systems, each differing by the sign of one of the magnon/photon
coupling strengths. This simple difference, originating from the various
coupling phases in the system, is shown to preserve, or destroy, two potential
applications of hybrid photon/magnon systems, namely dark mode memories and
cavity-mediated coupling. The observable consequences of the coupling phase in
this system is akin to the manifestation of a discrete Pancharatnam-Berry
phase, which may be useful for quantum information processing
Interface trap density metrology from sub-threshold transport in highly scaled undoped Si n-FinFETs
Channel conductance measurements can be used as a tool to study thermally
activated electron transport in the sub-threshold region of state-of-art
FinFETs. Together with theoretical Tight-Binding (TB) calculations, this
technique can be used to understand the evolution of source-to-channel barrier
height (Eb) and of active channel area (S) with gate bias (Vgs). The
quantitative difference between experimental and theoretical values that we
observe can be attributed to the interface traps present in these FinFETs.
Therefore, based on the difference between measured and calculated values of
(i) S and (ii) |dEb/dVgs| (channel to gate coupling), two new methods of
interface trap density (Dit) metrology are outlined. These two methods are
shown to be very consistent and reliable, thereby opening new ways of analyzing
in situ state-of-the-art multi-gate FETs down to the few nm width limit.
Furthermore, theoretical investigation of the spatial current density reveal
volume inversion in thinner FinFETs near the threshold voltage.Comment: 12 figures, 13 pages, Submitted to Journal of Applied Physic
Gigahertz single-electron pumping mediated by parasitic states
In quantum metrology, semiconductor single-electron pumps are used to generate accurate electric currents with the ultimate goal of implementing the emerging quantum standard of the ampere. Pumps based on electrostatically defined tunable quantum dots (QDs) have thus far shown the most promising performance in combining fast and accurate charge transfer. However, at frequencies exceeding approximately 1 GHz the accuracy typically decreases. Recently, hybrid pumps based on QDs coupled to trap states have led to increased transfer rates due to tighter electrostatic confinement. Here, we operate a hybrid electron pump in silicon obtained by coupling a QD to multiple parasitic states and achieve robust current quantization up to a few gigahertz. We show that the fidelity of the electron capture depends on the sequence in which the parasitic states become available for loading, resulting in distinctive frequency-dependent features in the pumped current
Probing the Spin States of a Single Acceptor Atom
We demonstrate a single-hole transistor
using an individual acceptor
dopant embedded in a silicon channel. Magneto-transport spectroscopy
reveals that the ground state splits as a function of magnetic field
into four states, which is unique for a single hole bound to an acceptor
in a bulk semiconductor. The two lowest spin states are heavy (|<i>m</i><sub><i>j</i></sub>| = 3/2) and light (|<i>m</i><sub><i>j</i></sub>| = 1/2) hole-like, a two-level
system that can be electrically driven and is characterized by a magnetic
field dependent and long relaxation time, which are properties of
interest for qubits. Although the bulklike spin splitting of a boron
atom is preserved in our nanotransistor, the measured Landé
g-factors, |<i>g</i><sub><i>hh</i></sub>| = 0.81
± 0.06 and |<i>g</i><sub><i>lh</i></sub>|
= 0.85 ± 0.21 for heavy and light holes respectively, are lower
than the bulk value