This paper shows single electron transistor at room temperature,created on macroscopic system-the two-dimensional large area surface of our hydrogenated diamond like carbon thin film. Our results, free from the limitation of lowering the size of coulomb blockade in sub-nanometer range with the existing unprofitable process,are consistent with the theoretical results and will be relevant for future practical applications in the realm of atomic physics, quantum phenomenon and metrology.
In this work, we present a performance analysis of Field Effect Transistors based on recently fabricated 100% hydrogenated graphene (the so-called graphane) and theoretically predicted semi-hydrogenated graphene (i.e. graphone). The approach is based on accurate calculations of the energy bands by means of GW approximation, subsequently fitted with a three-nearest neighbor (3NN) sp3 tight-binding Hamiltonian, and finally used to compute ballistic transport in transistors based on functionalized graphene. Due to the large energy gap, the proposed devices have many of the advantages provided by …
Diamond field-effect transistors (FETs) have potential applications in power electronics and high-output high-frequency amplifications. In such applications, high charge-carrier mobility is desirable for a reduced loss and high-speed operation. We have recently fabricated diamond FETs with a hexagonal-boron-nitride gate dielectric and observed a high mobility above 300 cm$^{2}$V$^{-1}$s$^{-1}$. In this study, we examine which scattering mechanism limits the mobility of our FETs through theoretical calculations. Our calculations reveal that the dominant carrier scattering is caused by surface c…
We perform single- and multi-band Migdal-Eliashberg (ME) calculations with parameters exctracted from density functional theory (DFT) simulations to study superconductivity in the electric-field-induced 2-dimensional hole gas at the hydrogenated (111) diamond surface. We show that according to the Eliashberg theory it is possible to induce a high-T$_{\text{c}}$ superconducting phase when the system is field-effect doped to a surface hole concentration of $6\times10^{14}\,$cm$^{-2}$, where the Fermi level crosses three valence bands. Starting from the band-resolved electron-phonon spectral func…
Transistors operating at high frequencies are the basic building blocks of millimeter-wave communication and sensor systems. The high velocity and mobility of carriers in graphene can open way for ultra-fast group IV transistors with similar or even better performance than can be achieved with III-V based semiconductors. However, the progress of high-speed graphene transistors has been hampered due to fabrication issues, influence of adjacent materials, and self-heating effects. Here, we report a graphene field-effect transistor (FET) on a diamond substrate, with a $f_{max}$ up to 54 GHz for a…
We report on sub-bandgap optoelectronic phenomena of hydrogen-terminated diamond patterned with a submicron oxidized line. The line acts as an energy barrier for the two-dimensional hole gas located below the hydrogenated diamond surface. A photoconductive gain of the hole conductivity across the barrier is measured for sub-bandgap illumination. The findings are consistent with photogenerated electrons being trapped in defect levels within the barrier. We discuss the spatial and energetic characteristics of the optoelectronic phenomena, as well as possible photocurrent effects.
The spin-orbit couplings (SOCs) of hydrogenated and fluorinated graphenes are calculated from the first principles method. It is found that the SOC-induced band splittings near their Fermi energies can be significantly enhanced to the order of 10$^{-2}$ eV from the original about 10$^{-6}$ eV of the pure raphene, which is comparable to those found in the diamond and even the archetypal semiconductors. And two different mechanisms are proposed to explain the SOC enhancements in these two systems. The huge SOC enhancements are found to come not only from the sp$^3$ hybridization of carbon atoms,…
Field-effect transistors made of wide-bandgap semiconductors can operate at high voltages, temperatures and frequencies with low energy losses, and have been of increasing importance in power and high-frequency electronics. However, the poor performance of p-channel transistors compared with that of n-channel transistors has constrained the production of energy-efficient complimentary circuits with integrated n- and p-channel transistors. The p-type surface conductivity of hydrogen-terminated diamond offers great potential for solving this problem, but surface transfer doping, which is commonl…
Diamond has attracted attention as a next-generation semiconductor because of its various exceptional properties such as a wide bandgap and high breakdown electric field. Diamond field effect transistors, for example, have been extensively investigated for high-power and high-frequency electronic applications. The quality of their charge transport (i.e., mobility), however, has been limited due to charged impurities near the diamond surface. Here, we fabricate diamond field effect transistors by using a monocrystalline hexagonal boron nitride as a gate dielectric. The resulting high mobility o…
Fabrication of graphene field effect transistor is described which uses an intrinsic graphene on the surface of as deposited hydrogenated amorphous carbon films. Ambipolar characteristic has been demonstrated typical for graphene devices, which changes to unipolar characteristic if the surface graphene was etched in oxygen plasma. Because amorphous carbon films can be growth easily, with unlimited dimensions and no transfer of graphene is necessary, this can open new perspective for graphene electronics.
A single-hole transistor is patterned in a p-type, C-doped GaAs/AlGaAs heterostructure by AFM oxidation lithography. Clear Coulomb blockade resonances have been observed at T=300 mK. A charging energy of ~ 1.5 meV is extracted from Coulomb diamond measurements, in agreement with the lithographic dimensions of the dot. The absence of excited states in Coulomb diamond measurements, as well as the temperature dependence of Coulomb peak heights indicate that the dot is in the multi-level transport regime. Fluctuations in peak spacings larger than the estimated mean single-particle level spacing ar…
Undoped diamond, a remarkable bulk electrical insulator, exhibits a high surface conductivity in air when the surface is hydrogen-terminated. Although theoretical models have claimed that a two-dimensional hole gas is established as a result of surface energy band bending, no definitive experimental demonstration has been reported so far. Here, we prove the two-dimensional character of the surface conductivity by low temperature characterization of diamond in-plane gated field-effect transistors that enable the lateral confinement of the transistor's drain-source channel to nanometer dimension…
We introduce a computational approach to estimate the hardness and stiffness of diamond surfaces and nanoparticles by studying their elastic response to atomic nanoindentation. Results of our ab initio density functional calculations explain the observed hardness differences between different diamond surfaces and suggest bond stiffening in bare and hydrogenated fragments of cubic diamond and lonsdaleite. The increase in hardness and stiffness can be traced back to bond length reduction especially in bare nanoscale diamond clusters, a result of compression that is driven by the dominant role of…
The application of imaging techniques based on ensembles of nitrogen-vacancy (NV) sensors in diamond to characterise electrical devices has been proposed, but the compatibility of NV sensing with operational gated devices remains largely unexplored. Here we fabricate graphene field-effect transistors (GFETs) directly on the diamond surface and characterise them via NV microscopy. The current density within the gated graphene is reconstructed from NV magnetometry under both mostly p- and n-type doping, but the exact doping level is found to be affected by the measurements. Additionally, we obse…
Two novel properties, unique for semiconductors: a negative electron affinity [1-2], and a high p-type surface electrical conductivity [3-4], were discovered in diamond at the end of the last century. Both properties appear when the diamond surface is hydrogenated. A natural question arises: is the influence of the surface hydrogen on diamond limited only to the electrical properties? Here, we report the first observation of a transparency peak at 1328 cm-1 in IR absorption of hydrogen-terminated pure (undoped) nanodiamonds. This new optical property is ascribed to Fano-type destructive interf…
Hydrogenated diamond has been regarded as a promising material in electronic device applications, especially in field-effect transistors (FETs). However, the quality of diamond hydrogenation has not yet been established, nor has the specific orientation that would provide the optimum hydrogen coverage. In addition, most theoretical work in the literature use models with 100% hydrogenated diamond surfaces to study electronic properties, which is far from the experimentally observed hydrogen coverage. In this work, we have carried out a detailed study using fully atomistic reactive molecular dyn…
We use a simultaneous flow of ethylene and hydrogen gases to grow single wall carbon nanotubes by chemical vapor deposition. Strong coupling to the gate is inferred from transport measurements for both metallic and semiconducting tubes. At low-temperatures, our samples act as single-electron transistors where the transport mechanism is mainly governed by Coulomb blockade. The measurements reveal very rich quantized energy level spectra spanning from valence to conduction band. The Coulomb diamonds have similar addition energies on both sides of the semiconducting gap. Signatures of subbands po…
Single electron transistors (SETs) are fabricated by placing single walled carbon nanotubes (SWNTs) on a 100 nm wide local Al/Al2O3 bottom gate and then contacting with Pd electrodes. Coulomb oscillations up to 125 K were observed and charging energies of 12-15 meV with level spacing of ~5 meV were measured from the Couloumb diamond, in agreement with a dot size of ~100 nm, implying that the local gate defines the dot size by bending SWNT at the edges and controls its operation. This "mechanical template" approach may facilitate large scale fabrication of SET devices using SWNT.
We report electronic transport experiments on a graphene single electron transistor. The device consists of a graphene island connected to source and drain electrodes via two narrow graphene constrictions. It is electrostatically tunable by three lateral graphene gates and an additional back gate. The tunneling coupling is a strongly nonmonotonic function of gate voltage indicating the presence of localized states in the barriers. We investigate energy scales for the tunneling gap, the resonances in the constrictions and for the Coulomb blockade resonances. From Coulomb diamond measurements in…
We report magnetoresistance measurements of hydrogen-terminated (100)-oriented diamond surfaces where hole carriers are accumulated using an ionic-liquid-gated field-effect-transistor technique. Unexpectedly, the observed magnetoresistance is positive within the range of 2<T<10 K and -7<B<7 T, in striking contrast to the negative magnetoresistance previously detected for similar devices with (111)-oriented diamond surfaces. Furthermore we find: 1) magnetoresistance is orders of magnitude larger than that of the classical orbital magnetoresistance; 2) magnetoresistance is nearly independent of …
Graphene demonstrated potential for practical applications owing to its excellent electronic and thermal properties. Typical graphene field-effect transistors and interconnects built on conventional SiO2/Si substrates reveal the breakdown current density on the order of 1 uA/nm2 (i.e. 10^8 A/cm2) which is ~100\times larger than the fundamental limit for the metals but still smaller than the maximum achieved in carbon nanotubes. We show that by replacing SiO2 with synthetic diamond one can substantially increase the current-carrying capacity of graphene to as high as ~18 uA/nm2 even at ambient …
The interplay between spin and charge in solids is currently among the most discussed topics in condensed matter physics. Such interplay gives rise to magneto-electric coupling, which in the case of solids was named magneto-electric effect, as predicted by Curie on the basis of symmetry considerations. This effect enables the manipulation of magnetization using electrical field or, conversely, the manipulation of electrical polarization by magnetic field. The latter is known as the magnetocapacitance effect. Here, we show that non-equilibrium spin accumulation can induce tunnel magnetocapacita…
We have developed an etching process to fabricate a quantum dot and a nearby single electron transistor as a charge detector in a single layer graphene. The high charge sensitivity of the detector is used to probe Coulomb diamonds as well as excited spectrum in the dot, even in the regime where the current through the quantum dot is too small to be measured by conventional transport means. The graphene based quantum dot and integrated charge sensor serve as an essential building block to form a solid-state qubit in a nuclear-spin-free quantum world.
Hole doping can control the conductivity of diamond either through boron substitution, or carrier accumulation in a field-effect transistor. In this work, we combine the two methods to investigate the insulator-to-metal transition at the surface of nanocrystalline diamond films. The finite boron doping strongly increases the maximum hole density which can be induced electrostatically with respect to intrinsic diamond. The ionic gate pushes the conductivity of the film surface away from the variable-range hopping regime and into the quantum critical regime. However, the combination of the stron…
Diamond, a well-known wide-bandgap insulator, becomes a low-temperature superconductor upon substitutional doping of carbon with boron. However, limited boron solubility and significant lattice disorder introduced by boron doping prevent attaining the theoretically-predicted high-temperature superconductivity. Here we present an alternative co-doping approach, based on the combination of ionic gating and boron substitution, in hydrogenated thin films epitaxially grown on (111)- and (110)-oriented single crystals. Gate-dependent electric transport measurements show that the effect of boron dopi…
As wide bandgap electronic devices have continued to advance in both size reduction and power handling capabilities, heat dissipation has become a significant concern. To mitigate this, chemical vapor deposited (CVD) diamond has been demonstrated as an effective solution for thermal management of these devices by directly growing onto the transistor substrate. A key aspect of power and radio frequency (RF) electronic devices involves transient switching behavior, which highlights the importance of understanding the temperature dependence of the heat capacity and thermal conductivity when model…
We demonstrate the fabrication of a single electron transistor device based on a single ultra-small silicon quantum dot connected to a gold break junction with a nanometer scale separation. The gold break junction is created through a controllable electromigration process and the individual silicon quantum dot in the junction is determined to be a Si_170 cluster. Differential conductance as a function of the bias and gate voltage clearly shows the Coulomb diamond which confirms that the transport is dominated by a single silicon quantum dot. It is found that the charging energy can be as large…
Quantum confined devices of three-dimensional topological insulators have been proposed to be promising and of great importance for studies of confined topological states and for applications in low energy-dissipative spintronics and quantum information processing. The absence of energy gap on the TI surface limits the experimental realization of a quantum confined system in three-dimensional topological insulators. This communication reports on the successful realization of single-electron transistor devices in Bi$_2$Te$_3$ nanoplates by state of the art nanofabrication techniques. Each devic…
We report fast, simultaneous charge sensing and transport measurements of gate-defined carbon nanotube quantum dots. Aluminum radio frequency single electron transistors (rf-SETs) capacitively coupled to the nanotube dot provide single-electron charge sensing on microsecond timescales. Simultaneously, rf reflectometry allows fast measurement of transport through the nanotube dot. Charge stability diagrams for the nanotube dot in the Coulomb blockade regime show extended Coulomb diamonds into the high-bias regime, as well as even-odd filling effects, revealed in charge sensing data.
We present electrical data of silicon single electron devices fabricated with CMOS techniques and protocols. The easily tuned devices show clean Coulomb diamonds at T = 30 mK and charge offset drift of 0.01 e over eight days. In addition, the devices exhibit robust transistor characteristics including uniformity within about 0.5 V in the threshold voltage, gate resistances greater than 10 GΩ, and immunity to dielectric breakdown in electric fields as high as 4 MV/cm. These results highlight the benefits in device performance of a fully CMOS process for single electron device fabrication.
Spin-1/2 electrons are scattered through one or two diamond-like loops, made of quantum dots connected by one-dimensional wires, and subject to both an Aharonov-Bohm flux and (Rashba and Dresselhaus) spin-orbit interactions. With some symmetry between the two branches of each diamond, and with appropriate tuning of the electric and magnetic fields (or of the diamond shapes) this device completely blocks electrons with one polarization, and allows only electrons with the opposite polarization to be transmitted. The directions of these polarizations are tunable by these fields, and do not depend…
In this letter we report single-hole tunneling through a quantum dot in a two-dimensional hole gas, situated in a narrow-channel field-effect transistor in intrinsic silicon. Two layers of aluminum gate electrodes are defined on Si/SiO$_2$ using electron-beam lithography. Fabrication and subsequent electrical characterization of different devices yield reproducible results, such as typical MOSFET turn-on and pinch-off characteristics. Additionally, linear transport measurements at 4 K result in regularly spaced Coulomb oscillations, corresponding to single-hole tunneling through individual Cou…
Molecular states in a SINGLE PAIR of strongly coupled self-assembled InAs quantum dots are investigated using a sub-micron sized single electron transistor containing just a few pairs of coupled InAs dots embedded in a GaAs matrix. We observe a series of well-formed Coulomb diamonds with charging energy of less than 5 meV, which are much smaller than those reported previously. This is because electrons are occupied in molecular states, which are spread over both dots and occupy a large volume. In the measurement of ground and excited state single electron transport spectra with magnetic field,…
We review here some universal aspects of the physics of two-electron molecular transistors in the absence of strong spin-orbit effects. Several recent quantum dots experiments have shown that an electrostatic backgate could be used to control the energy dispersion of magnetic levels. We discuss how the generically asymmetric coupling of the metallic contacts to two different molecular orbitals can indeed lead to a gate-tunable Hund's rule in the presence of singlet and triplet states in the quantum dot. For gate voltages such that the singlet constitutes the (non-magnetic) ground state, one ge…
