Barrier Inhomogeneities Dominating Low-Frequency Excess Noise of Schottky Contacts

ABSTRACTWe introduce a new quantitative description for electronic noise at Schottky contacts. The model combines spatially inhomogeneous current transport across the interface with the modulation of the local barrier height due to trapping dynamics of charged states located at or close to the interface. The experimentally observed increase of noise power with decreasing temperature is explained by the inhomogeneity of the interface. Our model fits experimental data obtained from different silicide/silicon Schottky contacts and the detailed analysis of measured noise spectra yields information about the interfacial potential fluctuations.

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Nature of Low-Frequency Excess Noise in n-Type Gallium Nitride

MRS Proceedings ◽

10.1557/proc-622-t6.23.1 ◽

2000 ◽

Vol 622 ◽

Cited By ~ 2

Author(s):

C. F. Zhu ◽

W. K. Fong ◽

B. H. Leung ◽

C. C. Cheng ◽

C. Surya

Keyword(s):

Flicker Noise ◽

Power Spectra ◽

Low Frequency ◽

Excess Noise ◽

Rf Plasma ◽

Frequency Noise ◽

Noise Power ◽

Frequency Range ◽

X Ray Diffraction ◽

X Ray

ABSTRACTLow-frequency noise is investigated in n-type GaN film grown by rf-plasma assisted molecular beam epitaxy. The temperature dependence of the voltage noise power spectra, SV(f), was examined from 400K to 80K in the frequency range between 30Hz and 100KHz, which can be modeled as the superposition of 1/f (flicker) noise G-R noise. At f > 500 Hz the noise is dominated by G-R noise with activation energies of 360meV and 65meV from the conduct band. The results clearly demonstrate the trap origin for both the 1/f noise and G-R noise. At the low-frequency range the fluctuation was dominated by 1/f noise. To determine the origin of the noise we considered both the bulk mobility fluctuation and the trap fluctuation models. Our experimental results showed that rapid thermal annealing (RTA) at 800°C resulted in over one order of magnitude decrease in the Hooge parameter. Annealing at temperatures in excess of 1000°C resulted in significant increase in the noise. Photoluminescence and x-ray diffraction measurements also showed that the crystallinity of the films improved with RTA at 800°C with an accompanying reduction in deep levels. Annealing at 900°C and 1000°C resulted in an increase in the FWHM of the x-ray diffraction indicative of thermal decomposition of the materials. The results are in excellent agreement with the trend of Hooge parameters as a function of annealing temperature, strongly indicating trap origin of the observed 1/f noise.

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MEASUREMENT OF FLICKER NOISE AS A DIAGNOSTIC TOOL FOR HOT-ELECTRON DEGRADATION IN GaN-BASED LEDS

Fluctuation and Noise Letters ◽

10.1142/s0219477507004045 ◽

2007 ◽

Vol 07 (04) ◽

pp. L419-L428

Author(s):

W. K. FONG ◽

K. K. LEUNG ◽

H. F. LUI ◽

P. K. A. WAI ◽

C. SURYA ◽

...

Keyword(s):

Diagnostic Tool ◽

Flicker Noise ◽

Light Output ◽

Low Frequency ◽

Excess Noise ◽

Frequency Noise ◽

Noise Power ◽

Hot Electron ◽

Noise Power Spectral Density ◽

Rate Of Increase

Hot-electron stressing on GaN -based light emitting diodes (LEDs) has been performed using a dc stressing current. Detailed characterizations on the degradations in the optoelectronic and low-frequency noise properties of the devices have been conducted. Experimental results on I-V, electroluminescence (EL) and the integrated light output of the devices exhibit significant degradations with the stress time. Investigations on the low-frequency excess noise of the devices show that the degradations of the device properties arise from the generation of interface states at the InGaN / GaN heterointerface due to hot-electron stressing. Over two orders of magnitude increase in the current noise power spectral density, SI(f), is typically observed prior to the failure of the devices. Furthermore, it is shown that the initial rate of increase in SI(f) resulting from a dc current stress time of 48 hours is strongly correlated to the lifetimes of the devices demonstrating that flicker noise measurement can be used as a diagnostic tool for hot-electron hardness of the device.

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STUDY OF LOW-FREQUENCY EXCESS NOISE IN Ga-POLARITY GaN EPITAXIAL LAYERS

Fluctuation and Noise Letters ◽

10.1142/s0219477501000445 ◽

2001 ◽

Vol 01 (04) ◽

pp. R163-R174 ◽

Cited By ~ 1

Author(s):

J. Q. XIE ◽

W. K. FONG ◽

B. H. LEUNG ◽

C. F. ZHU ◽

C. SURYA ◽

...

Keyword(s):

Thin Films ◽

Flicker Noise ◽

Substantial Reduction ◽

Power Spectra ◽

Low Frequency ◽

Buffer Layers ◽

Excess Noise ◽

Rf Plasma ◽

Noise Power ◽

Scattering Rate

We report detailed investigations of low-frequency excess noise in Ga -polarity GaN thin films deposited by RF-plasma assisted molecular beam epitaxy. The noise properties of the GaN thin films deposited with and without the intermediate-temperature buffer layers (ITBL) are studied in detailed to examine the effects of the ITBL on the noise. Substantial reduction in the flicker noise levels are observed for samples grown on ITBLs with a Hooge parameter of 3×10-4, which is believed to be the lowest, to date, reported for GaN material. At low-temperatures, Lorentzian bumps originating from the generation-recombination processes are observed. Detailed studies of the temperature dependencies of the voltage noise power spectra have led to the formulation of a model for the observed low-frequency fluctuations. The model stipulates that the phenomenon arises from the thermally activated trapping and detrapping of carriers. The process results in the correlated fluctuations in the carrier number and the Coulombic scattering rate. Quantitative computation shows that number fluctuation dominates in our samples. Numerical evaluation of the deep-levels indicates substantial reduction in the trap density for the Ga -polarity GaN films.

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DEGRADATION OF LOW-FREQUENCY NOISE IN AlGaN/GaN HEMTS DUE TO HOT-ELECTRON STRESSING

Fluctuation and Noise Letters ◽

10.1142/s0219477507003726 ◽

2007 ◽

Vol 07 (01) ◽

pp. L91-L100 ◽

Cited By ~ 1

Author(s):

SHRAWAN K. JHA ◽

CHANG-FEI ZHU ◽

MANFRED H. PILKUHN ◽

CHARLES SURYA ◽

HEINZ SCHWEIZER

Keyword(s):

Low Frequency ◽

Degradation Process ◽

Open Circuit ◽

Excess Noise ◽

Second Phase ◽

Frequency Noise ◽

Noise Power ◽

Hot Electron ◽

Low Frequency Noise ◽

Gan Hemts

We report on the degradation of low-frequency excess noise in recessed gate AlGaN/GaN HEMTs due to hot-electron stressing. The I-V characteristics and the low-frequency noise power spectral densities, SV(f), of the open circuit voltage fluctuations across the drain source terminal were characterized with the stress time. Based on these results, we observed that the overall low-frequency noise degradation process can be identified to occur in two distinct phases. In the first phase, devices initially show fluctuations in the noise properties around a relatively constant average value. Detailed characterizations of the gate-source bias, VGS, dependence of SV(f) at cryogenic temperatures indicate signature-patterns in the variations of SV(f) as a function of VGS. This is shown to arise from the modulation of the percolation paths of the carriers in the two-dimensional electron gas (2DEG). The onset of the second phase of degradation arises from the irreversible generation of interface states at the AlGaN/GaN hetero-interface.

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Study of 14.9 MeV Neutron Irradiation Effects on Ni/GaN Schottky Contacts Using Low‐Frequency Noise Spectroscopy

physica status solidi (a) ◽

10.1002/pssa.201900701 ◽

2019 ◽

Vol 217 (7) ◽

pp. 1900701

Author(s):

Yuan Ren ◽

Leidang Zhou ◽

Kang Zhang ◽

Liang Chen ◽

Xiaoping Ouyang ◽

...

Keyword(s):

Neutron Irradiation ◽

Low Frequency ◽

Schottky Contacts ◽

Frequency Noise ◽

Low Frequency Noise ◽

Irradiation Effects ◽

Noise Spectroscopy

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D-Dot Sensor Response Improvement in the Evaluation of High-Power Microwave Pulses

Electronics ◽

10.3390/electronics10020123 ◽

2021 ◽

Vol 10 (2) ◽

pp. 123

Author(s):

Jacek Jakubowski ◽

Marek Kuchta ◽

Roman Kubacki

Keyword(s):

High Power ◽

Critical Infrastructure ◽

Quantitative Description ◽

Low Frequency ◽

Digital Processing ◽

High Energy ◽

Time Duration ◽

High Power Microwave ◽

Time Waveform ◽

Power Microwave

This article investigates the issue of measuring high-power microwave (HPM) pulses. The high energy of these pulses poses a significant threat to many electronic systems, including those used to manage critical infrastructure. This work focuses on requirements for a potential portable measurement device and suggests the application of a method for this purpose, involving the use of a D-dot sensor and a rapid A/D converter. The applied converter enables recording the time waveform on the measuring chain output, also in the case of repetition and time duration of HPM signals. The authors also present a quantitative description of signal processing by the analogue section of the measurement chain solution presented herein and suggest algorithms for digital processing of the signals, the objective of which is to minimize low-frequency interference in the process of reconstructing the time waveform of an electric field using numerical integration.

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Carotid and aortic baroreflexes of the rat: II. Open-loop frequency response and the blood pressure spectrum

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.2000.279.5.r1922 ◽

2000 ◽

Vol 279 (5) ◽

pp. R1922-R1933 ◽

Cited By ~ 20

Author(s):

Barry R. Dworkin ◽

Xiaorui Tang ◽

Alan J. Snyder ◽

Susan Dworkin

Keyword(s):

Blood Pressure ◽

Venous Pressure ◽

Low Frequency ◽

Noise Spectrum ◽

Open Loop ◽

Step Response ◽

Algebraic Solution ◽

Noise Power ◽

Vascular Conductance ◽

Aortic Depressor Nerve

To determine the relationship between blood pressure (BP) variability and the open-loop frequency domain transfer function (TF) of the baroreflexes, we measured the pre- and postsinoaortic denervation (SAD) spectra and the effects of periodic and step inputs to the aortic depressor nerve and isolated carotid sinus of central nervous system-intact, neuromuscular-blocked (NMB) rats. Similar to previous results in freely moving rats, SAD greatly increased very low frequency (VLF) (0.01–0.2 Hz) systolic blood pressure (SBP) noise power. Step response-frequency measurements for SBP; interbeat interval (IBI); venous pressure; mesenteric, femoral, and skin blood flow; and direct modulation analyses of SBP showed that only VLF variability could be substantially attenuated by an intact baroreflex. The −3-dB frequency for SBP is 0.035–0.056 Hz; femoral vascular conductance is similar to SBP, but mesenteric vascular conductance has a reliably lower and IBI has a reliably higher −3-dB point. The overall open-loop transportation lag, of which ≤0.1 s is neural, is ≈1.07 s. Constrained algebraic solution, over a range of frequencies, of the pre- and postSAD endogenous noise spectra and the independently determined relative frequency and absolute lag measurements was used to calculate the absolute gain for the open-loop TF. The average gain at 0.02 Hz, the frequency of maximum sensitivity, was 1.47 (95% confidence interval = ±0.48), which agrees well with estimates for the dog reversible sinus. We found that, in the NMB rat, the effects of SAD on the BP noise spectrum were accounted for by the open-loop properties of the baroreflex.

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