We analyze resonant tunneling subject to a non-adiabatic time-dependent bias-voltage through an asymmetric single molecular quantum dot with coupling between the electronic and vibrational degrees of freedom using a {\em Tien-Gordon-type} rate equation. Our results clearly exhibit the appearance of photon-assisted satellites in the current-voltage characteristics and the elimination of hot-phonon-induced negative differential conductance with increasing ac driving amplitude for an asymmetric system. This can be ascribed to an {\em ac-induced suppression} of unequilibrated (hot) phonons in an asymmetric system.
We evaluate the current distribution for a single-electron transistor with intermediate strength tunnel conductance. Using the Schwinger-Keldysh approach and the drone (Majorana) fermion representation we account for the renormalization of system parameters. Nonequilibrium effects induce a lifetime broadening of the charge-state levels, which suppress large current fluctuations.
The thermal dependence of the electrical conductance of the single-electron transistor (SET) in the zero-bias Kondo regime is discussed. An exact mapping to the universal curve for the symmetric Anderson model is established. Linear, the mapping is parametrized by the Kondo temperature and the charge in the Kondo cloud. Illustrative numerical renormalization-group results, in excellent agreement with the mapping, are presented.
We study field-effect transistors realized from VO2 nanobeams with HfO2 as the gate dielectric. When heated up from low to high temperatures, VO2 undergoes an insulator-to-metal transition. We observe a change in conductance (~ 6 percent) of our devices induced by gate voltage when the system is in the insulating phase. The response is reversible and hysteretic, and the area of hysteresis loop becomes larger as the rate of gate sweep is slowed down. A phase lag exists between the response of the conductance and the gate voltage. This indicates the existence of a memory of the system and we dis…
A numerical renormalization-group survey of the zero-bias electrical conductance through a quantum dot embedded in the conduction path of a nanodevice is reported. The results are examined in the light of a recently derived linear mapping between the temperature-dependent conductance and the universal function describing the conductance for the symmetric Anderson model. A gate potential applied to the conduction electrons is known to change markedly the transport properties of a quantum dot side-coupled to the conduction path; in the embedded geometry here discussed, a similar potential is sho…
We show that the conductance of Spin Field Effect Transistors (SPINFET) [Datta and Das, Appl. Phys. Lett., Vol. 56, 665 (1990)] is affected by a single (non-magnetic) impurity in the transistor's channel. The extreme sensitivity of the amplitude and phase of the transistor's conductance oscillations to the location of a single impurity in the channel is reminiscent of the phenomenon of universal conductance fluctuations in mesoscopic samples and is extremely problematic as far as device implementation is concerned.
The linear conductance of the single electron transistor is determined in the high temperature limit. Electron tunneling is treated nonperturbatively by means of a path integral formulation and the conductance is obtained from Kubo's formula. The theoretical predictions are valid for arbitrary conductance and found to explain recent experimental data.
The quantum conductance of the single-electron tunneling (SET) transistor is investigated in this paper by the functional integral approach. The formalism is valid for arbitrary tunnel resistance of the junctions forming the SET transistor at any temperature. The path integrals are evaluated by the semiclassical method to yield an explicit non-perturbation form of the quantum conductance of the SET transistor. An anomaly of the quantum conductance is found if the tunnel resistances are much smaller than the quantum resistance. The dependence of the conductance on the gate voltage is also discu…
We report on experimental results for the conductance of metallic single-electron transistors as a function of temperature, gate voltage and dimensionless conductance. In contrast to previous experiments our transistor layout allows for a direct measurement of the parallel conductance and no ad hoc assumptions on the symmetry of the transistors are necessary. Thus we can make a comparison between our data and theoretical predictions without any adjustable parameter. Even for rather weakly conducting transistors significant deviations from the perturbative results are noted. On the other hand, …
The fundamental property of most single-electron devices with quasicontinuous quasiparticle spectrum on the island is the periodicity of their transport characteristics in the gate voltage. This property is robust even with respect to placing the ferroelectric insulators in the source and drain tunnel junctions. We show that placing the ferroelectric inside the gate capacitance breaks this periodicity. The current-voltage characteristics of this SET strongly depends on the ferroelectric polarization and shows the giant memory-effect even for negligible ferroelectric hysteresis making this devi…
Using a time-dependent Anderson Hamiltonian, a quantum dot with an ac voltage applied to a nearby gate is investigated. A rich dependence of the linear response conductance on the external frequency and driving amplitude is demonstrated. At low frequencies the ac potential produces sidebands of the Kondo peak in the spectral density of the dot, resulting in a logarithmic decrease in conductance over several decades of frequency. At intermediate frequencies, the conductance of the dot displays an oscillatory behavior due to the appearance of Kondo resonances of the satellites of the dot level. …
We study the temperature and gate voltage dependence of the conductance of the single electron transistor focusing on highly conducting devices. Electron tunneling is treated nonperturbatively by means of path integral Monte Carlo techniques and the conductance is determined from the Kubo formula. A regularized singular value decomposition scheme is employed to calculate the conductance from imaginary time simulation data. Our findings are shown to bridge between available analytical results in the semiclassical and perturbative limits and are found to explain recent experimental results in a …
The conductance modulations in spin field-effect transistors under finite bias voltages were studied. It was shown that when a finite bias voltage is applied between two terminals of a spin field-effect transistor, the spin precession states of injected spin-polarized electrons in the semiconductor channel of the device will depend not only the gate-voltage controlled Rashba spin-orbit coupling but also depend on the bias voltage and, hence, the conductance modulation in the device due to Rashba spin-orbit coupling may also depend sensitively on the bias voltage.
While Single Molecule Transistors have been employed in laboratory research for a number of years, there remain many details related to charge transport that have yet to be delineated. We have used the technique of electromigration to create a nanometer-size gap for hosting a single molecule in the narrowest portion of a gold wire defined by electron beam lithography. A recently synthesized Borromean Ring complex was used as the active molecular element of the transistor devices. It is well established in Single Molecule Transistors that, for sweeps of source-drain voltage, a region of zero co…
We report on combined measurements of heat and charge transport through a single-electron transistor. The device acts as a heat switch actuated by the voltage applied on the gate. The Wiedemann-Franz law for the ratio of heat and charge conductances is found to be systematically violated away from the charge degeneracy points. The observed deviation agrees well with the theoretical expectation. With large temperature drop between the source and drain, the heat current away from degeneracy deviates from the standard quadratic dependence in the two temperatures.
We measure the small signal, 1 GHz source-drain dynamical conductance of a back-gated single-walled carbon nanotube field effect transistor at both low and high dc bias voltages. At all bias voltages, the intrinsic device dynamical conductance at 1 GHz is identical to the low frequency dynamical conductance, consistent with the prediction of a cutoff frequency much higher than 1 GHz. This work represents a significant step towards a full characterization of a nanotube transistor for RF and microwave amplifiers.
Dots are ideal systems to study fundamentals on heat transfer at the nanoscale and promising nanoscale heat-engines and thermal devices. Here, we report on the validation of our theoretical model on the thermal conductance of a metallic dot single-electron transistor (md-SET) by a recent experiment on the low-T thermal conductance. We compare with the experiment, we emphasize the physics interpretation and characteristic values and we apply the model to evaluate the operation the md-SET as heat-switch. Perfect agreement is shown between the calculated and the measured charge conductance G, hea…
Silicene (a monolayer of silicon atoms) is a quantum spin-Hall insulator, which undergoes a topological phase transition into other insulators by applying external field such as electric field, photo-irradiation and antiferromagnetic order. We investigate the electronic and transport properties of silicene nanoribbons based on the Landauer formalism. We propose to determine topological phase transitions by measuring the density of states and conductance. The conductance is quantized and changes its value when the system transforms into different phases. We show that a silicene nanoribbon near …
We propose and analyze a novel dual-gate Spin Field Effect Transistor (SpinFET) with half-metallic ferromagnetic source and drain contacts. The transistor has two gate pads that can be biased independently. It can be switched ON or OFF with a few mV change in the differential bias between the two pads, resulting in extremely low dynamic power dissipation during switching. The ratio of ON to OFF conductance remains fairly large (~ 60) up to a temperature of 10 K. This device also has excellent inverter characteristics, making it attractive for applications in low power and high density Boolean …
The current through ferromagnetic single-electron transistors (SET's) is considered. Using path integrals the linear response conductance is formulated as a function of the tunnel conductance vs. quantum conductance and the temperature vs. Coulomb charging energy. The magneto-resistance of ferromagnet-normal metal-ferromagnet (F-N-F) SET's is almost independent of the Coulomb charging energy and is only reduced when the transport dwell time is longer than the spin-flip relaxation time. In all-ferromagnetic (F-F-F) SET's with negligible spin-flip relaxation time the magneto-resistance is calcul…
In this paper, we analyze vibration-assisted sequential tunneling (including current-voltage characteristics and zero-frequency shot noise) through a molecular quantum dot with two electronic orbitals asymmetrically coupled to the internal vibration. We employ rate equations for the case of equilibrated phonons, and strong Coulomb blockade. We find that a system with a strongly phonon-coupled ground state orbital and weakly phonon-coupled excited state orbital exhibits strong negative differential conductance; and it also shows super-Poissonian current noise. We discuss in detail the reasons a…
We incorporate an Al-AlO_x-Al single-electron transistor as the gate of a narrow (~100 nm) metal-oxide-semiconductor field-effect transistor (MOSFET). Near the MOSFET channel conductance threshold, we observe oscillations in the conductance associated with Coulomb blockade in the channel, revealing the formation of a Si single-electron transistor. Abrupt steps present in sweeps of the Al transistor conductance versus gate voltage are correlated with single-electron charging events in the Si transistor, and vice versa. Analysis of these correlations using a simple electrostatic model demonstrat…
Electron transport through molecular quantum dots coupled to a single vibrational mode is studied in the Kondo regime. We apply a generalized Schrieffer-Wolff transformation to determine the effective low-energy spin-spin-vibron-interaction. From this model we calculate the nonlinear conductance and find Kondo sidebands located at bias-voltages equal to multiples of the vibron frequency. Due to selection rules, the side-peaks are found to have strong gate-voltage dependences, which can be tested experimentally. In the limit of weak electron-vibron coupling, we employ a perturbative renormaliza…
The linear and nonlinear transport properties of the single-electron transistor at the degeneracy point are investigated for the case of weak single-mode tunnel junctions. Two opposing scenarios are considered, distinguished by whether or not electrons can propagate coherently between the two tunnel junctions. Each of these two scenarios corresponds to the realization of a different multichannel Kondo effect - the two-channel Kondo effect in the case where coherent propagation is allowed, and the four-channel Kondo effect in the absence of coherent propagation. A detailed analysis of the linea…
By using the Schwinger-Keldysh approach, we evaluate the current noise and the charge noise of the single-electron transistor (SET) in the regime of large charge fluctuations caused by large tunneling conductance. Our result interpolates between previous theories; the "orthodox" theory and the "co-tunneling theory". We find that the life-time broadening effect suppresses the Fano factor below the value estimated by the previous theories. We also show that the large tunnel conductance does not reduce the energy sensitivity so much. Our results demonstrate quantitatively that SET electrometer ca…
Electron transport through a single-level quantum dot weakly coupled to Luttinger liquid leads is considered in the master equation approach. It is shown that for a weak or moderately strong interaction the differential conductance demonstrates resonant-like behavior as a function of bias and gate voltages. The inelastic channels associated with vibron-assisted electron tunnelling can even dominate electron transport for a certain region of interaction strength. In the limit of strong interaction resonant behavior disappears and the differential conductance scales as a power low on temperature…
Two key subjects stand out in the pursuit of semiconductor research: material quality and contact technology. The fledging field of atomically thin transition metal dichalcogenides (TMDCs) faces a number of challenges in both efforts. This work attempts to establish a connection between the two by examining the gate-dependent conductance of few-layer (1-5L) WSe2 field effect devices. Measurements and modeling of the subgap regime reveal Schottky barrier transistor behavior. We show that transmission through the contact barrier is dominated by thermionic field emission (TFE) at room temperature…
We review some experimental and theoretical results on the metal-to-insulator transition (MIT) observed at zero magnetic field (B=0) in several two-dimensional electron systems (2DES). Scaling of the conductance and magnetic field dependence of the conductance provide convincing evidence that the MIT is driven by Coulomb interactions among the carriers and is dramatically sensitive to spin polarization of the carriers.
We study transport through a Coulomb blockaded topologically nontrivial superconducting wire (with Majorana end states) contacted by metallic leads. An exact formula for the current through this interacting Majorana single-charge transistor is derived in terms of wire spectral functions. A comprehensive picture follows from three different approaches. We find Coulomb oscillations with universal halving of the finite-temperature peak conductance under strong blockade conditions, where the valley conductance mainly comes from elastic cotunneling. The nonlinear conductance exhibits finite-voltage…
Stubbed waveguides and stub transistors are candidates for next generation electronic devices. In particular, such structures may be used in spintronics-based quantum computation, because of its ability to induce spin-polarized carriers. In this paper, we present the simulation of the conductance of the stub transistor (single and double-gated), modeled with a nearest-neighbor tight-binding Hamiltonian. The oscillatory behavior of the channel conductance with the applied stub voltage is observed.
A single-electron transistor (SET) in a magnetic field irradiated with microwaves is studied theoretically in non-equilibrium Kondo regime. The two fold effect of frequency--Ω--microwaves is considered as follows: the oscillations in the voltage with frequency Ωand in the coupling parameters with frequency Ω/p (p\in\mathbb{N}). We describe the system by the Kondo model at a specific point in the Toulouse limit. A non-perturbative technique is proposed, namely, the non-equilibrium Green's functions and physical observables are averaged over a period of 2πp/Ω. When the microwave irradiation is c…
The analytical electrical transport model of the Silicene, a single layer of sp3 bonded silicon atoms in the honeycomb lattice structure as a channel in the field effect transistor configuration is presented in this paper. Although the carrier concentration of the Silicene shows similar behavior to Graphene, there are some differences in the conductance behavior. Presented model shows increment in the total carrier and the conductance with the gate voltage as expected for conventional semiconductors which affected by the temperature only in the neutrality point. The minimum conductance is incr…
Phosphorene, a honeycomb structure of black phosphorus, was isolated recently. We investigate electric properties of phosphorene nanoribbons based on the tight-binding model. A prominent feature is the presence of quasi-flat edge bands entirely detached from the bulk band. We explore the mechanism of the emergence of the quasi-flat bands analytically and numerically from the flat bands well known in graphene by a continuous deformation of a honeycomb lattice. The quasi-flat bands can be controlled by applying in-plane electric field perpendicular to the ribbon direction. The conductance is swi…
The interplay between Coulomb interaction and orbital symmetry produces specific transport characteristics in molecular single electron transistors (SET) that can be considered as the fingerprints of the contacted molecule. Specifically we predict, for a benzene SET, selective conductance suppression and the appearance of negative differential conductance when changing the contacts from para to meta configuration. Both effects originate from destructive interference in transport involving states with orbital degeneracy.
We study the contact resistance and the transfer characteristics of back-gated field effect transistors of mono- and bi-layer graphene. We measure specific contact resistivity of ~7kohm*um2 and ~30kohm*um2 for Ni and Ti, respectively. We show that the contact resistance is a significant contributor to the total source-to-drain resistance and it is modulated by the back-gate voltage. We measure transfer characteristics showing double dip feature that we explain as the effect of doping due to charge transfer from the contacts causing minimum density of states for graphene under the contacts and …
We demonstrate that the conductance through a single-electron transistor at low temperature is in quantitative agreement with predictions of the equilibrium Anderson model. When an unpaired electron is localized within the transistor, the Kondo effect is observed. Tuning the unpaired electron's energy toward the Fermi level in nearby leads produces a cross-over between the Kondo and mixed-valence regimes of the Anderson model.
Transistors, regardless of their size, rely on electrical gates to control the conductance between source and drain contacts. In atomic-scale transistors, this conductance is exquisitely sensitive to single electrons hopping via individual orbitals. Single-electron transport in molecular transistors has been previously studied using top-down approaches to gating, such as lithography and break junctions. But atomically precise control of the gate - which is crucial to transistor action at the smallest size scales - is not possible with these approaches. Here, we used individual charged atoms, m…
The linear transport properties of a model molecular transistor with electron-electron and electron-phonon interactions were investigated analytically and numerically. The model takes into account phonon modulation of the electronic energy levels and of the tunnelling barrier between the molecule and the electrodes. When both effects are present they lead to asymmetries in the dependence of the conductance on gate voltage. The Kondo effect is observed in the presence of electron-phonon interactions. There are important qualitative differences between the cases of weak and strong coupling. In t…
Ultrathin (~3 quintuple layer) field-effect transistors (FETs) of topological insulator Bi2Se3 are prepared by mechanical exfoliation on 300nm SiO2/Si susbtrates. Temperature- and gate-voltage dependent conductance measurements show that ultrathin Bi2Se3 FETs are n-type, and have a clear OFF state at negative gate voltage, with activated temperature-dependent conductance and energy barriers up to 250 meV.
We study a ballistic spin field-effect transistor (SFET) with special attention to the issue of multi-channel effects. The conductance modulation of the SFET as a function of the Rashba spin-orbit coupling strength is numerically examined for the number of channels ranging from a few to close to 100. Even with the ideal spin injector and collector, the conductance modulation ratio, defined as the ratio between the maximum and minimum conductances, decays rapidly and approaches one with the increase of the channel number. It turns out that the decay is considerably faster when the Rashba spin-o…
We report electronic transport measurements of single-molecule transistor devices incorporating bipyridyl-dinitro oligophenylene-ethynylene dithiol (BPDN-DT), a molecule known to exhibit conductance switching in other measurement configurations. We observe hysteretic conductance switching in 8% of devices with measurable currents, and find that dependence of the switching properties on gate voltage is rare when compared to other single-molecule transistor devices. This suggests that polaron formation is unlikely to be responsible for switching in these devices. We discuss this and alternative …
A rate equation formalism is used to determine the effect of electron-phonon coupling on the conductance of a molecule. Interplay between the phonon-induced renormalization of the density of states on the quantum dot and the phonon-induced renormalization of the dot-lead coupling is found to be important. Whether or not the phonons are able to equilibrate in a time rapid compared to the transit time of an electron through the dot is found to affect the conductance. Observable signatures of phonon equilibration are presented.
An analytical expression is derived for the conductance modulation of a ballistic two dimensional Datta-Das Spin Field Effect Transistor (SPINFET) as a function of gate voltage. Using this expression, we show that the recently observed conductance modulation in a two-dimensional SPINFET structure does not match the theoretically expected result very well. This calls into question the claimed demonstration of the SPINFET and underscores the need for further careful investigation.
Tunnel transport of interacting spin-polarized electrons through a single-level vibrating quantum dot in external magnetic field is studied. By using density matrix method, the current-voltage characteristics and the dependence of conductance on temperature of a single-electron transistor were calculated. We found that a lifting of Coulomb blockade in external magnetic field happens in stages. The Franck-Condon steps associated with inelastic electron tunneling in our case are doubled due to contribution of two Zeeman-split levels in electron transport. The doubling of steps can be also observ…
The chemical stability of graphene and other free-standing two-dimensional crystals means that they can be stacked in different combinations to produce a new class of functional materials, designed for specific device applications. Here we report resonant tunnelling of Dirac fermions through a boron nitride barrier, a few atomic layers thick, sandwiched between two graphene electrodes. The resonant peak in the device characteristics occurs when the electronic spectra of the two electrodes are aligned. The resulting negative differential conductance persists up to room temperature and is gate v…
Graphene field effect transistors commonly comprise graphene flakes lying on SiO2 surfaces. The gate-voltage dependent conductance shows hysteresis depending on the gate sweeping rate/range. It is shown here that the transistors exhibit two different kinds of hysteresis in their electrical characteristics. Charge transfer causes a positive shift in the gate voltage of the minimum conductance, while capacitive gating can cause the negative shift of conductance with respect to gate voltage. The positive hysteretic phenomena decay with an increase of the number of layers in graphene flakes. Self-…
We studied the spin-dependent quantum transport properties using a simple modelling of a Datta-Das spin transistor. We refine previous results by accounting the propagation medium changes of opacity felt by itinerant electrons, when the gate-voltage is switched on and modelling them via the transversal energy levels mismatch. Monitoring the topological-dependent conductance, we are able to identify the device operating points. If the incoming electrons energy approaches the biased-induced barriers height, the spin-resolved conductance oscillations become significant. In a zero temperature pict…
We study the influence of Coulomb interaction on the thermoelectric transport coefficients for a metallic single-electron transistor. By performing a perturbation expansion up to second order in the tunnel-barrier conductance, we include sequential and cotunneling processes as well as quantum fluctuations that renormalize the charging energy and the tunnel conductance. We find that Coulomb interaction leads to a strong violation of the Wiedemann-Franz law: the Lorenz ratio becomes gate-voltage dependent for sequential tunneling, and is increased by a factor 9/5 in the cotunneling regime. Final…
We present an approach for time-dependent quantum transport based on a self-consistent non-equilibrium Green function formalism. The technique is applied to a ballistic carbon nanotube transistor in the presence of a time harmonic signal at the gate. In the ON state the dynamic conductance exhibits plasmonic resonant peaks at terahertz frequencies. These vanish in the OFF state, and the dynamic conductance displays smooth oscillations, a signature of single particle quantum effects. We show that the nanotube kinetic inductance plays an essential role in the high-frequency behavior.
It is understood that molecular conjugation plays an important role in charge transport through single-molecule junctions. Here, we investigate electron transport through an anthraquinone based single-molecule three-terminal device. With the use of an electric-field induced by a gate electrode, the molecule is reduced resulting into a ten-fold increase in the off-resonant differential conductance. Theoretical calculations link the change in differential conductance to a reduction-induced change in conjugation, thereby lifting destructive interference of transport pathways.
We propose a magnetic topological transistor based on MnBi$_{2}$Te$_{4}$, in which the "on" state (quantized conductance) and the "off" state (zero conductance) can be easily switched by changing the relative direction of two adjacent electric fields (parallel vs. antiparallel) applied within a two-terminal junction. We explain that the proposed magnetic topological transistor relies on a novel mechanism due to the interplay of topology, magnetism, and layer degrees of freedom in MnBi$_{2}$Te$_{4}$. Its performance depends substantially on film thickness and type of magnetic order. We show tha…
Thermoelectric properties of a C60 molecular transistor are studied using Green function formalism in linear response regime. A tight-binding model is used to investigate the effect of the dimerization and coupling geometry on the electrical conductance, thermopower, and figure of merit. Increase of the connection points between the molecule and electrodes results in decrease of the number of the peaks of the electrical conductance owing to the interference effects. In addition, oscillation of the thermopower is reduced by increase of the connection points. It is also observed that the kind of…
The understanding of various types of disorders in atomically thin transition metal dichalcogenides (TMDs), including dangling bonds at the edges, chalcogen deficiencies in the bulk, and charges in the substrate, is of fundamental importance for their applications in electronics and photonics. Because of the imperfections, electrons moving on these two-dimensional (2D) crystals experience a spatially non-uniform Coulomb environment, whose effect on the charge transport has not been microscopically studied. Here, we report the mesoscopic conductance mapping in monolayer and few-layer MoS2 field…
We investigate electronic transport in Josephson junctions formed by single-walled carbon nanotubes coupled to superconducting electrodes. We observe enhanced zero-bias conductance (up to 10e^2/h) and pronounced sub-harmonic gap structures in differential conductance, which arise from the multiple Andreev reflections at superconductor/nanotube interfaces. The voltage-current characteristics of these junctions display abrupt switching from the supercurrent branch to resistive branch, with a gate-tunable switching current ranging from 50 pA to 2.3 nA. The finite resistance observed on the superc…
We consider tunneling transport through a Mn$_{12}$ molecular magnet using spin density functional theory. A tractable methodology for constructing many-body wavefunctions from Kohn-Sham orbitals allows for the determination of spin-dependent matrix elements for use in transport calculations. The tunneling conductance at finite bias is characterized by peaks representing transitions between spin multiplets, separated by an energy on the order of the magnetic anisotropy. The energy splitting of the spin multiplets and the spatial part of their many-body wave functions, describing the orbital de…
The vertical stacking of van der Waals (vdW) materials introduces a new degree of freedom to the research of two-dimensional (2D) systems. The interlayer coupling strongly influences the band structure of the heterostructures, resulting in novel properties that can be utilized for electronic and optoelectronic applications. Based on microwave microscopy studies, we report quantitative electrical imaging on gated molybdenum disulfide (MoS2)/tungsten diselenide (WSe2) heterostructure devices, which exhibit an intriguing anti-ambipolar effect in the transfer characteristics. Interestingly, in the…
Systems of quantum dots (QD) connected to leads exhibit periodic conductance peaks as a function of gate voltage arising from the Coulomb blockade effect \cite{review1,review2,review3}. Much effort goes into minimizing the size of QDs and reaching the scale of single molecules \cite{molecular1,molecular2,molecular3} which could serve as nanoelectronic circuit components such as transistors. Connecting molecules or nanoparticles to external leads cannot be achieved by the traditional methods used in semiconductor based QDs, hence, controlling the coupling to nanoparticle QDs is a major technica…
We have fabricated and characterized a single hole transistor in an undoped AlGaAs-GaAs heterostructure. Our device consists of a p-type quantum dot, populated using an electric field rather than modulation doping. Low temperature transport measurements reveal periodic conductance oscillations due to Coulomb blockade. We find that the low frequency charge noise is comparable to that in modulation-doped GaAs single electron transistors (SETs), and almost an order of magnitude better than in silicon SETs.
