Dielectric Polarization Noise Research Articles

Evaluation of a Gate Capacitance in the Sub-aF Range for a Chemical Field-Effect Transistor With a Si Nanowire Channel

An evaluation of the gate capacitance of a field-effect transitor (FET), whose channel length and width are several ten nanometer, is a key point for sensors applications. However, experimental and precise evaluation of capacitance in the attofarad range or less has been extremely difficult. Here, we report an extraction of the capacitance down to 0.55 aF for a Si FET with a nanoscale wire channel, whose width and length are 15 and 50 nm, respectively. The extraction can be achieved by using a combination of four kinds of measurements: current characteristics modulated by double gates, random-telegraph-signal noise induced by trapping and detrapping of a single electron, dielectric polarization noise, and current characteristics showing Coulomb blockade at low temperature. The extraction of such a small gate capacitance enables us to evaluate electron mobility in a nanoscale wire by using a classical model of current characteristics of an FET.

A silicon nanowire ion-sensitive field-effect transistor with elementary charge sensitivity

We investigate the mechanisms responsible for the low-frequency noise in liquid-gated nanoscale silicon nanowire field-effect transistors (SiNW-FETs) and show that the charge-noise level is lower than elementary charge. Our measurements also show that ionic strength of the surrounding electrolyte has a minimal effect on the overall noise. Dielectric polarization noise seems to be at the origin of the 1/f noise in our devices. The estimated spectral density of charge noise Sq=1.6×10−2 e/Hz1/2 at 10 Hz opens the door to metrological studies with these SiNW-FETs for the electrical detection of a small number of molecules.

A charge-integration readout circuit with a linear-mode silicon avalanche photodiode for a photon-number resolving detector

A charge-integration readout circuit for a photon-number resolving detector for visible or near-infrared wavelength is presented. In the scheme, photons are converted into electric carriers by a Si APD operating in the linear mode. To read the small number of photo-carriers generated by the Si APD, a charge-integration readout circuit is used. The entire circuit operates at 77 K. The main noise of the readout circuit is attributed to dielectric polarization noise, which is dominant at the operating temperature. The noise of the readout circuit was reduced to 3.0 electrons averaged by a period of 40 ms.

Ultralow-noise near-infrared detection system with a Si p-i-n photodiode.

Noises associated with materials and devices in the readout circuits for a Si p-i-n photodiode have been measured. The dielectric polarization noise of the materials and devices near the gate circuit of the junction field-effect transistor used for the preamplifier determined the photodetection limits of photodiodes with a diameter smaller than several millimeters. We fabricated an ultralow-noise photodetection system, minimizing the polarization noise as much as possible. The readout noises of the system were 10 and 18 electrons in a correlated double sample for 0.1- and 1-mm-diameter Si p-i-n photodiodes at 77 K, respectively.

1/f dielectric polarization noise in silicon p-n junctions

Dielectric polarization noise in silicon p-n junctions was measured at low leakage current, less than 1×10−17 A, and at temperatures between 110 and 200 K. The power spectra of the noise voltages exhibit 1/f characteristics, where f is the frequency. The dielectric loss of the p-n junctions, which was derived from the 1/f noise by using the fluctuation-dissipation theorem, is proportional to the temperature, and is almost independent of the characteristics of the p-n junctions.

High-sensitivity dielectric polarization noise measurements

Techniques for measurement of low-level dielectric polarization noise spectra over a broad dynamic range are described. The method provides a powerful probe of 1/f noise and near-equilibrium dynamics in nonconducting materials of interest such as glass formers, liquid crystals, polymers, or ferroelectrics. Dielectric polarization noise was measured via voltage fluctuations in a capacitance cell filled with sample material. Measurements were carried out in the temperature range 80–400 K on glycerol and poly-vinyl-chloride near their respective glass transitions. To maximize the dynamic range and sensitivity and limit effects of stray capacitance an ultralow-noise junction field-effect transistor based preamplifier was operated adjacent to the sample in vacuum within the low-temperature cryostat. The technique offers potentially greater accuracy than susceptibility measurements in low-loss regimes, and may be useful in single-electron-transistor applications.

Dielectric polarization noise through the glass transition.

Measurements of thermal dielectric polarization noise were performed on an organic glass former. The temperature and frequency dependence of the noise was investigated in glycerol in the vicinity of its glass transition. Polarization fluctuations were observed via current or voltage noise, which were produced within a sample capacitance cell. The predictions of the fluctuation-dissipation theorem proved valid even on entering a nonequilibrium regime near the glass transition. Noise spectra exhibit power-law behavior similar to $\frac{1}{f}$ noise at lower temperatures. The measurements provide a useful spectroscopy of spontaneous structural rearrangements in dielectric and biological materials.

1/f Dielectric Fluctuations at the Glass Transition

AbstractThe temperature and frequency dependence of thermal dielectric polarization noise was investigated in glycerol and PVC in the vicinity of their glass transitions. Polarization fluctuations were observed via voltage noise which was produced within a sample capacitance cell. The high sensitivity and accuracy of the technique provides a powerful probe of dynamics in low-loss regimes of various materials. Noise spectra had 1/fβ form at lower temperatures just below the glass transition. In glycerol, the spectral exponent decreased smoothly with temperature, extrapolating to 1, i.e. 1/f noise, near T° where relaxation times diverge. The results support the idea that a glassy phase transition occurs in the static limit.