Current Noise Behavior Research Articles

Forward current transport and noise behavior of GaN Schottky diodes

In this work, we first measure the forward temperature-dependent current-voltage (<i>T</i>-<i>I</i>-<i>V</i>) characteristics of the GaN-based Schottky diodes grown on the bulk GaN substrates, and then study the transport mechanisms of the forward current and the low-frequency current noise behaviors under various injection levels. The results are obtained below. 1) In a forward high-bias region the thermionic emission current dominates, and the extracted barrier height is about 1.25 eV at <i>T</i> = 300 K, which is close to the value measured by capacitance-voltage sweeping. 2) In a forward low-bias region (<i>V</i> < 0.8 V) the current is governed by the trap assist tunneling process, having an ideality factor much larger than 1, and the derived barrier height is about 0.92 eV at <i>T</i> = 300 K, which indicates that the conductive dislocation should be mainly responsible for the excessive leakage current, having a reduced barrier around the core of dislocations. 3) The Lorentzian noise appears only at very small current (<i>I</i> < 1 μA) and low frequency (<i>f</i> < 10 Hz), whose typical time constant is extracted to be about 30 ms, depending on the multiple capture and release process of electrons via defects. 4) At a higher frequency and current, the low-frequency 1/<i>f</i> noise becomes important and the corresponding coefficient is determined to be about 1.1, where the transport is affected by the random fluctuation of the Schottky barrier height.

Effect of cobalt-60 gamma irradiation on graphene: Raman and field emission investigations

Electrophoretically deposited graphene (HG) on silicon is irradiated using a cobalt-60 gamma radiation source with the radiation dose up to 22.7 kGy. The effect of gamma irradiation on the field emission current noise behavior of HG is investigated. The power spectra of pristine and irradiated HG exhibit 1/fα type of noise, with α ∼ 0.8. The magnitude of noise power is observed to increase with the radiation dose. The variations in the turn on field and noise power in the emission current are attributed to the structural modifications of HG, as revealed from the field emission scanning electron microscopic and Raman spectroscopic studies.

Correlation of Current Noise Behavior and Dark Spot Formation in Organic Light-Emitting Diodes

A correlation between current 1/f noise and dark spot formation is reported. Our results show that the dark spot is primarily correlated to current 1/f noise slope; the higher the slope, the poorer the interface, and the more abnormal dark spot growth rate and the shorter lifetime. Besides, there is a correlation between current 1/f noise magnitude and the dark spot initial size. A higher 1/f noise magnitude generally indicates a larger dark spot initial size. A seemingly identical current-voltage curve does not render the same characteristics of dark spot formation, which can be clearly distinguished from the subtle difference in 1/f noise behavior. The noise measurement can be used to predicate device lifetime and degradation behavior.

Low-frequency noise and interface states in GaAs homojunction far-infrared detectors

Low-frequency noise characteristics of p-GaAs homojunction interfacial work-function internal photoemission (HIWIP) far-infrared (FIR) detectors are reported. The noise was found to exhibit 1/f behavior related to interface states at frequencies below 1 kHz and frequency independent shot noise at higher frequencies. The noise expressions correctly predict the dark current noise behavior, and provide a means of estimating both the gain and energy distribution of the interface states. The interface state density is estimated to be in the order of 10/sup 11/ cm/sup -2/. It has been shown that the estimated gain and noise equivalent power are in good agreement with the previous results obtained via optical measurements.

Low-frequency drain current noise behavior of InP based MODFET's in the linear and saturation regime

This paper describes a detailed experimental study of the low-frequency (LF) drain current noise behavior of InP based MODFET's in a broad operation regime, spanning both linear and saturation operation. The noise power spectral density S/sub lD/ of the predominantly 1/f noise is studied as a function of the gate and drain bias. The experimental noise behavior is compared with available analytical models. It is shown that there is a reasonable agreement between the data and the theoretical models in linear operation. However, no accurate theory exists for the saturation regime. Therefore, an empirical analytical description is proposed, which provides a good approximation for the measurement data base. Furthermore, it can be used as a starting point for phase noise simulations in high-frequency nonlinear circuits.

Thermodynamics of Nonlinearity and Noise in Diodes

The irreversible thermodynamics of a nonlinear diode are discussed by considering a circuit in which a biased diode exchanges noise power with a linear resistor at a different temperature. By applying the Onsager reciprocity relations to the two cross terms involving the rectification of thermal noise, and the generation of current noise by the diode, respectively, an equation is obtained relating the nonlinearity of the diode and a parameter which specifies its current-noise behavior. The implications of this equation are discussed in relation to the existence of a maximum value of the nonlinearity. The analysis predicts that a reverse current will flow through the diode when the resistor is at a lower temperature, and an experiment to confirm this is reported briefly.