Dependence Of Low-frequency Noise Research Articles

Temperature dependence of conduction and low frequency noise characteristics in GaN Schottky barrier diodes

In this paper, the forward bias conduction and low frequency noise (LFN) characteristics of GaN Schottky barrier diodes (SBDs) have been measured and studied in the temperature range from 300 K to 450 K. Based on I–V measured results, the temperature dependence of ideality factor and zero bias Schottky barrier height reveals the inhomogeneities of Schottky barriers at the metal-semiconductor (MS) interface. Further study of the LFN measured results shows that the flicker noise ([Formula: see text] noise) is the main component of LFN in GaN SBDs. The current dependence of LFN indicates the influences of the Schottky barrier and the series resistance on [Formula: see text] noise, and the temperature dependence of LFN is analyzed according to Luo’s model and the barrier inhomogeneities model.

Temperature Dependence of Low Frequency Noise in Silicon on Insulator Tunneling Field Effect Transistor.

In this work, noise mechanism of a tunneling field-effect transistor (TFET) on a silicon-on-insulator substrate was studied as a function of temperature. The results show that the drain current and subthreshold slope increase with increase in temperature. This temperature dependence is likely caused by the generation of greater current flow owing to decreased silicon band gap and leakage. Further, the TFET noise decreases with increase in temperature. Therefore, the effective tunneling length between the source and the channel appears to decrease and Poole-Frenkel tunneling occurs.

1/f Noise in InAs/InAsSb Superlattice Photoconductors

This article concerns the temperature dependence of low-frequency noise measured in the temperature range of 77–300 K in InAs/InAsSb superlattice photoconductors optimized for long-wavelength infrared (LWIR) and very long-wavelength infrared (VLWIR) spectral range. The differences in the T-dependence and the magnitude of 1/f noise, observed for LWIR and VLWIR photoconductors, are connected with different scattering mechanisms. Using the Hooge empirical model of 1/f noise and modeling of the total mobility, it is suggested that either the phonon-related or the defect-related mobility fluctuations can be responsible for the measured noise depending on the mechanism which determines the total mobility. In the VLWIR photoconductors, the defect-related 1/f noise prevails, while the phonon-related component dominates in the LWIR detector. The latter is best described by the Melkonyan et al. ’s mobility fluctuation model, which assumes the phonon scattering as the origin of 1/f noise. It roughly explains the T-dependence and predicts the value to within the one order of magnitude.

Gate Voltage Dependence of Low Frequency Noise in Tunneling Field Effect Transistors.

In this paper, the dependency of low frequency noise as a function of the gate voltage was examined for tunneling field effect transistors (TFETs). When the level of gate voltage is low, the tunneling width of the TFETs is large. Thus, electrons move via the trap instead of tunneling directly. On the other hand, when the level of gate voltage is high, the tunneling width of the TFETs becomes narrow. Thus, when the gate voltage is low, the noise level of TFETs is high because electrons pass through the trap. However, when the gate voltage is high, electrons pass directly from valence band of source to conduction band of drain, so the noise level is low. Finding the voltage suitable for this TFET is important to determine the optimum conditions for generating BTBT when measuring TFETs and to reduce noise.

Understanding the bias dependence of low frequency noise in single layer graphene FETs.

This letter investigates the bias-dependent low frequency noise of single layer graphene field-effect transistors. Noise measurements have been conducted with electrolyte-gated graphene transistors covering a wide range of gate and drain bias conditions for different channel lengths. A new analytical model that accounts for the propagation of the local noise sources in the channel to the terminal currents and voltages is proposed in this paper to investigate the noise bias dependence. Carrier number and mobility fluctuations are considered as the main causes of low frequency noise and the way these mechanisms contribute to the bias dependence of the noise is analyzed in this work. Typically, normalized low frequency noise in graphene devices has been usually shown to follow an M-shape dependence versus gate voltage with the minimum near the charge neutrality point (CNP). Our work reveals for the first time the strong correlation between this gate dependence and the residual charge which is relevant in the vicinity of this specific bias point. We discuss how charge inhomogeneity in the graphene channel at higher drain voltages can contribute to low frequency noise; thus, channel regions nearby the source and drain terminals are found to dominate the total noise for gate biases close to the CNP. The excellent agreement between the experimental data and the predictions of the analytical model at all bias conditions confirms that the two fundamental 1/f noise mechanisms, carrier number and mobility fluctuations, must be considered simultaneously to properly understand the low frequency noise in graphene FETs. The proposed analytical compact model can be easily implemented and integrated in circuit simulators, which can be of high importance for graphene based circuits' design.

A New Interpretation for the Anomalous Channel-Length Dependence of Low-Frequency Noise in Quasi-Ballistic Transistors

The operating regime of MOS transistors shifts from collision-dominated drift-diffusion (DD) to less-collision quasi-ballistic (QB) regime. The impact of transport mechanism on the low-frequency noise (LFN) is not well studied for QB devices. Most of the studies rely on the existing theories that were developed for DD-based devices to study LFN even in nanoscale regime. Validity of these models is questionable. In this letter, we extend the conventional carrier-number and correlated-mobility fluctuation model to the QB regime. The model is in accordance with the “apparent mean free path” $(\lambda _{\textit {app}})$ model, which predicts scattering limited noise mechanism in the QB regime. The model is validated with LFN measurement data for III-V QB devices, and shows good agreement with the expected behavior.

Temperature and field dependent low frequency noise characterization of Ge n-FETs

We report temperature (RT-150 K) and field dependent low frequency noise measurements on Ge n-FETs. Specifically, we delineate the temperature, field, and interfacial layer (GeON vs. GeO2) dependence of the gate overdrive index (β) on corresponding changes in volume interface trap density (Nit) and mobility (μ). For Nit < 1 × 1020 cm−3 eV−1, the dominant noise mechanism, number or mobility fluctuation, depends on the change in μ, but for Nit > 1 × 1020 cm−3eV−1 near the conduction band edge, changes in μ as well as Nit determine the noise mechanism. Finally, we show that the β values of Ge n-FETs are significantly different from conventional Si transistors as well as Ge p-FETs at RT and 150 K due to much higher Nit and/or μ values of the Ge n-FETs.

High Thermal Stability of GaN Schottky Diode with Diamond-Like Carbon (DLC) Anode Design

High breakdown voltage and thermally stable AlGaN/GaN Schottky barrier diodes (SBDs) were fabricated using diamond-like carbon (DLC) anode design on a silicon (111) substrate. The DLC metal-hydrocarbon target in this study is tungsten-carbide and this film coating was prepared by reactive DC magnetron sputtering in a high temperature chamber. Based on the measured Raman spectrum, a broad peak with two shoulders at approximately 1365 cm−1 (D peak) and 1570 cm−1 (G peak) can be observed and the intensity of D peak versus G peak for DLC in this study is about 1.37 by considering both coefficient of thermal expansion and conductivity. The lower serial resistance was observed in Ni/DLC anode SBD and this characteristic was concluded that the junction heat during high current operation was dissipated through the surface DLC anode immediately and thus the thermal accumulation induced resistance was improved. Temperature dependent low frequency noise (LFN) and reverse recovery measurements both indicated that the Ni/DLC anode design exhibited a highly potential for being operated at high switching frequencies and high temperatures with low switching loss.

Low Frequency Noise Characterization and Signal-to-Noise Ratio Optimization for Silicon Hall Cross Sensors

In this paper, silicon-based Hall cross sensors with different device dimensions and carrier densities are designed and fabricated. Low frequency noise behavior regarding to the device dimension and carrier density of the Hall cross sensors has been successfully characterized. Based on the measured $1/f$ -dependent low frequency noise spectral density and the theoretically calculated geometrical factors using a finite-element analysis tool, the noise voltage is calculated and Hooge's constant is reliably extracted. The signal-to-noise ratio is thus calculated and experimentally verified. This paper provides a guidance for the optimal design of Hall cross sensors.

Band-Edge Noise Spectroscopy of a Magnetic Tunnel Junction

We propose a conceptually new way to gather information on the electron bands of buried metal(semiconductor)/insulator interfaces. The bias dependence of low frequency noise in Fe$_{1-x}$V$_{x}$/MgO/Fe (0 $<$ x $<$ 0.25) tunnel junctions show clear anomalies at specific applied voltages, reflecting electron tunneling to the band edges of the magnetic electrodes. The change in magnitude of these noise anomalies with the magnetic state allows evaluating the degree of spin mixing between the spin polarized bands at the ferromagnet/insulator interface. Our results are in qualitative agreement with numerical calculations.

Angular Dependence of Low-Frequency Noise in Al$_{2}$O$_{3}$-Based Magnetic Tunnel Junction Sensors With Conetic Alloy

We demonstrated the noise performances of Al2O3-based magnetic tunnel junction sensors (MTJs) in the low-frequency regimes. Conetic alloy Ni77Fe14Cu5Mo4 was deposited as both the MTJ pinned layer and free layer because of its superb magnetically soft properties. A rotating magnetic field was employed to investigate the angular dependence of the MTJ low-frequency noise. Hooge parameter was applied for parameterizing the low-frequency noise. The measurement results demonstrate that the Hooge parameters are angular-dependent and they exhibit a linear relation with respect to the angular magnetoresistive susceptibility. It can be also observed that the Hooge parameters possess a higher value when the Conetic MTJs are in the region of antiparallel state. These results indicate that the magnetic fluctuations in the ferromagnetic layers contribute to the low-frequency noise level in Conetic MTJ sensors.

Area Dependent Low Frequency Noise in Metal Oxide Based Resistive Random Access Memory

Metal oxide based resistance random access memory (RRAM) has been extensively studied as one of the most promising candidate for next generation nonvolatile memory; however the current conduction mechanism is not yet clearly understood. To tackle this problem, low frequency noise behavior in metal oxide based RRAM device has been investigated in this work. Together with DC current voltage characteristics, it confirms that for the low resistance state, current conduction is localized without an area dependence, whereas, for the high resistance state, it is a uniform leakage current throughout the whole device area. This is consistent with the filament type resistive switching phenomenon in such devices.

Magnetic field dependence of low frequency noise in tunnel magnetoresistance heads

Field dependence of low frequency noise in tunnel magnetoresistance (TMR) heads with different barrier materials of TiO2, Al2O3, and MgO has been studied. It is found that for MgO-TMR heads, the noise amplitude increases as the sensor is driven from parallel to antiparallel magnetization configurations. However, this field dependence of the noise is not magnetic in origin and can be accounted for by the coherent tunneling mechanism in MgO-TMR heads. For TiO2- and Al2O3-TMR heads, low frequency noise is generally independent of magnetic field when the heads are biased properly by hard bias. A noise spike related to a resistance jump in the transfer curve is measured in a head without proper hard bias. Field-dependent low frequency noise is observed for TMR heads without hard bias. The noise amplitude follows the sensitivity function of the sensor and can be attributed to the thermally activated magnetization fluctuations. Spin transfer (ST) effect on low frequency noise was examined by noise measurements of field dependence at different current directions. Extra noise appears when the TMR head is in antiparallel magnetization configurations. The results suggest that the ST-induced extra noise can be either pure 1/f noise or the combination of both 1/f and random telegraph noises.

An investigation of the magnetic state dependent low frequency noise in magnetic tunnel junctions

The low frequency noise in magnetic tunnel junctions was studied as a function of applied magnetic field. In magnetic states where the magnetization is reversing, the measurement indicates a 1/f2 spectrum whereas at all other applied fields a 1/f spectrum is observed. The 1/f2 spectra are found to be an artifact of the magnetic after effect. Without the artificial influence of the magnetic after effect, only 1/f spectra are observed.

Thermal dependence of low-frequency noise in polysilicon thin film transistors

Thermal dependence of low frequency noise in low temperature (≤ 600 °C) polysilicon thin film transistors is studied in devices biased from weak to moderate inversion and operating in the linear mode. Drain current noise spectral density, measured in the temperature range from 260 K to 310 K, is thermally activated following the Meyer Neldel rule. Analysis of the thermal activation of noise, supported by the theory of trapping/detrapping processes of carriers into oxide traps located close to the interface, leads to the calculation of the deep state interface distribution in function of the Meyer Neldel characteristic energy.

The Effect of Single-Halo Doping on the Low-Frequency Noise Performance of Deep Submicrometer MOSFETs

In this letter, the low-frequency noise performance of single-halo (SH) devices is reported, and the physical mechanisms are identified. Experimental results show that, at constant gate overdrive voltages, SH devices show reduced low-frequency noise levels compared to the conventional devices. However, under constant current bias conditions, the noise reduction is less substantial. Low-frequency noise dependence on channel length is also investigated for SH devices based on the electrical measurements and analytical calculations

Dependence of low frequency noise in SiGe heterojunction bipolar transistors on the dimensional and structural features of extrinsic regions

In this paper, the effects of different transistor design aspects on the noise behavior of SiGe heterojunction bipolar transistors have been investigated. Selectively implanted collector, although retards the base push-out, does not deteriorate the noise characteristics. Moreover, a higher dopant implant in the extrinsic base region intended for a smaller base resistance does not deteriorate the noise characteristics. While the interface between the SiGe epitaxial and polycrystalline layers does not have any detrimental impact, the emitter-poly overlap significantly influences both the DC and the noise characteristics. Smaller emitter-poly overlap results in an increased non-ideal base current at lower bias voltages and produces appreciable generation–recombination noise. For all the transistors, except for the ones with smaller emitter-poly overlap, the base current noise power spectral density shows a near quadratic dependence on the base current, where the noise is believed to originate mostly from the superposition of the generation–recombination noise in the intrinsic emitter–base junction. The base current noise power spectral density for the transistors with a smaller emitter-poly overlap shows a near linear dependence on the base current, which results from an increased contribution from the trap-assisted tunneling fluctuations of the minority carriers at the surface of the emitter–base junction.

Low-Frequency Noise Measurement-Based Reliability Testing of VLSI Interconnects with Different Geometry

Low-frequency noise measurements were performed on thin metallic very large-scale integration (VLSI) interconnects of three different geometries. These measurements were carried out under stressing current densities between 1.0/spl times/10/sup 5/ A/cm/sup 2/ and 2.2/spl times/10/sup 6/ A/cm/sup 2/ at different ambient temperatures up to 280/spl deg/C, in order to investigate the dependence of low-frequency noise on the geometrical shape of the VLSI interconnects. The behavior of these samples under these conditions is analyzed in this letter.

Power and temperature dependence of low frequency noise in AlGaN∕GaN transmission line model structures

The low-frequency noise in AlGaN∕GaN transmission line model structures has been investigated for a wide range of ambient temperatures and dissipated powers. A deviation of low-frequency noise from a 1∕f dependence has been observed upon increasing the applied voltage. The effect correlates with the nonlinearity of current-voltage characteristics (CVC). The concept of nonequilibrium 1∕f noise has been introduced to explain 1∕f noise enhancement. A qualitative model connecting non-equilibrium noise with nonlinearity of the CVC via a common origin—nonuniform overheating of the structures—has been suggested. Furthermore, deviations of equilibrium noise from the 1∕f law at low temperatures have been observed and studied.

Lateral base design rules for optimized low-frequency noise of differentially grown SiGe heterojunction bipolar transistors

The low-frequency noise dependence on lateral design parameters was investigated for SiGe heterojunction bipolar transistors fabricated by differential epitaxy. The low-frequency noise was found to vary substantially as a function of the extrinsic base design. The dominant noise sources were located either at the interface between the polycrystalline and epitaxial Si/SiGe base, in the epitaxial Si/SiGe base link region, in the base–emitter depletion region, or at the thin SiO 2 interface layer between the polysilicon and monosilicon emitter. Boron was found to passivate interfacial traps, acting as low-frequency noise sources. Generation–recombination noise with a strong dependence on the lateral electrical field was observed for some of the designs.