Liquid-gated silicon nanowire (NW) field effect transistors (FETs) are fabricated and their transport and dynamic properties are investigated experimentally and theoretically. Random telegraph signal (RTS) fluctuations were registered in the nanolength channel FETs and used for the experimental and theoretical analysis of transport properties. The drain current and the carrier interaction processes with a single trap are analyzed using a quantum-mechanical evaluation of carrier distribution in the channel and also a classical evaluation. Both approaches are applied to treat the experimental data and to define an appropriate solution for describing the drain current behavior influenced by single trap resulting in RTS fluctuations in the Si NW FETs. It is shown that quantization and tunneling effects explain the behavior of the electron capture time on the single trap. Based on the experimental data, parameters of the single trap were determined. The trap is located at a distance of about 2 nm from the interface Si/SiO2 and has a repulsive character. The theory of dynamic processes in liquid-gated Si NW FET put forward here is in good agreement with experimental observations of transport in the structures and highlights the importance of quantization in carrier distribution for analyzing dynamic processes in the nanostructures.

The current through a p-in diode containing a layer of self-assembled InAs quantum dots in the intrinsic region is investigated. A series of peaks is observed in the differential conductance below the flat band regime which we attribute to electron tunneling in the quantum dot and wetting layer states, combining the carrier recombination and the carrier relaxation effects. This phenomenon is investigated numerically on the basis of a master equation model. Criteria for the observability of the charging of individual quantum dots are discussed. A key point is the presence of Coulomb screening as otherwise the long-range interdot interactions smear out the energy level spectrum.

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Articles you may be interested inThe basic reason for enhanced electron capture time, s c , of the oxide single trap dependence on drain current in the linear operation regime of p þ -p-p þ silicon field effect transistors (FETs) was established, using a quantum-mechanical approach. A strong increase of s c slope dependence on channel current is explained using quantization and tunneling concepts in terms of strong field dependence of the oxide layer single trap effective cross-section, which can be described by an amplification factor. Physical interpretation of this parameter deals with the amplification of the electron cross-section determined by both decreasing the critical field influence as a result of the minority carrier depletion and the potential barrier growth for electron capture. For the NW channel of n þ -p-n þ FETs, the experimentally observed slope of s c equals (À1). On the contrary, for the case of p þ -p-p þ Si FETs in the accumulation regime, the experimentally observed slope of s c equals (À2.8). It can be achieved when the amplification factor is about 12. Extraordinary high capture time slope values versus current are explained by the effective capture cross-section growth with decreasing electron concentration close to the nanowire-oxide interface. V C 2015 AIP Publishing LLC.

Devices with metallic nanoconstrictions functionalized by organic molecules are promising candidates for the role of functional devices in molecular electronics. However, at the moment little is known about transport and noise properties of nanoconstriction devices of this kind. In this paper, transport properties of bare gold and molecule-containing tunable cross-section nanoconstrictions are studied using low-frequency noise spectroscopy. Normalized noise power spectral density (PSD) S /I dependencies are analyzed for a wide range of sample resistances R from 10 Ohm to 10 MOhm. The peculiarities and physical background of the flicker noise behavior in the low-bias regime are studied. It is shown that modification of the sample surface with benzene-1,4-dithiol molecules results in a decrease of the normalized flicker noise spectral density level in the ballistic regime of sample conductance. The characteristic power dependence of normalized noise PSD as a function of system resistance is revealed. Models describing noise behavior for bare gold and BDT modified samples are developed and compared with the experimental data for three transport regimes: diffusive, ballistic and tunneling. Parameters extracted from models by fitting are used for the characterization of nanoconstriction devices.

Dependency of both source-drain current and current sensitivity of nanosize ISFET biosensor vs. concentration of DNA molecules in aqueous solution theoretically is investigated. In calculations it is carried out effects concerning charge carriers distribution in current channel and concerning carriers' mobility behavior in high electrical fields in the channel. The influence of DNA molecules on the work of ISFET biosensors is manifested by a change in the magnitude of the gate surface charge. Starting with fairly low concentrations of DNA, ISFET sensors respond to the presence of DNA molecules in an aqueous solution which is manifested by modulation of channel conductance and therefore the source-drain current changes of the field-effect transistor. It is shown that the current sensitivity with respect to concentration of DNA molecules linearly depends on the source-drain voltage and reaches high values.