摘要:

In this review paper, we summerize the field and current instabilities that occur when the conductivity decreases more than linearly with increasing field, or increases sufficient steeply with increased current density. In both cases well defined transition ranges exist that causes a chaotic development of field-or current-inhomogeneities, respectively. These are the ranges in which substantial additional low-frequency electronic noise is generated that shows a typical 1/f behavior. Field instabilities occur in a range of an N-shaped current-voltage characteristic that result in high-field domains which can be stationary or move through the device and cause a stationary or oscillating reduction in current. The latter, as the Gunn effect, enjoys technical application as an ac generator. In CdS the negative differential conductivity regime is trap-controlled and thereby kinetic effects are slowed down so that they can be observed visually, using the Franz-Keldysh effect. During such observation, chaotic effects can be seen before the periodic oscillations are organized, and cause a substantial increase in low-frequency noise. The chaotic initiation of well organized periodically moving high-field domains are discussed in a phase-portrait analysis of the nonlinear dynamics for pattern formation in semiconductor devices. Also in an S-shaped characteristic that is initiated by substantial Joule’s heating and yields current channel formation, current instabilities can occur that lead to low frequency noise. The related phenomena are briefly summerized in this review. The experimental evidence of these chaotic developments of field- and current-instabilities is shown during the oral presentation in a movie, using electro-optical or electro-thermo-optical effects for visualization. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.58288

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

The Hooge parameter of the heavily doped InAs heterostructure decreased monotonically from2×10−3at the room temperature down to5×10−4at 50K. The dependence of the Hooge parameter of the various high mobility compound semiconductors on the temperature were summarized and interpreted in terms of the scattering mechanisms together with some comments on the absolute values of the Hooge parameter. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.58289

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

The transport of charge carriers in conducting layers generate excess low frequency noise which is 1/fatype. The main problem is if 1/f fluctuation is caused by fluctuation of number of carriers acting in transport or by mobility fluctuation due to scattering process. The objective of our research consisted in finding a correlation between the noise spectral density and nonlinearity on one hand and device time stability and reliability on the other. The noise of thick film resistor pastes 2041 and 8039 (10 k&OHgr;/sq.) was measured on resistors dimensions of0.3×0.3&hthinsp;mmand1×1&hthinsp;mm.The resistors were terminated by Ag/Pd and Ag conductors. Experimentally was observed, that noise spectral density is inversely proportional to the square of the sample length. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.58290

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

From our method of phonon density of states superposition method it is inferred that a possible connection between 1/f noise parameter and the Eliashberg function could exist. According to this hypothesis, the temperature dependence of the 1/f noise parameter would follow the energy dependence of the Eliashberg function. The existing noise data for tin(Sn). polycrystalline aluminum(Al) and a copper(Cu) nanobridge are compared with the corresponding Eliashberg functions. Striking resemblances are found. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.58284

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

The 1/f noise of 10 different ungated 2DEG structures based on InP substrates with InGaAs channels was investigated in the frequency range from 0.4 Hz to 100 kHz at temperatures between 80 K and 320 K. In spite of various channel designs (with mobilities between 6470 cm2/Vs and 11800 cm2/Vs), a clear dependence of the total Hooge parameter on the channel mobility was found. From samples with undoped channels the correlation&agr;H&hthinsp;tot∼&mgr;tot−2.6was obtained at room temperature. The lowest Hooge parameter&agr;H&hthinsp;tot≈1.5⋅10−5was observed for the samples having the highest mobilities and is attributed to two-dimensional phonon scattering processes. This value agrees quite well with the parameter proposed by Handel’s theory for umklapp processes. In contrast to this, the Hooge parameter of a sample with channel doping was found to be much smaller due to the presence of impurity scattering. Temperature dependent noise measurements revealed a significant dependence of&agr;H&hthinsp;toton various scattering mechanisms. Considering Matthiessen’s rule and the electron energy distribution, the separation of optical and acoustical phonon scattering as well as impurity scattering allows an exact description of the temperature dependent&agr;(T)H&hthinsp;tot.Furthermore, the Hooge parameters&agr;(T)H&hthinsp;acand&agr;(T)H&hthinsp;optrelated to acoustical and optical phonon scattering processes are found to be temperature dependent material-specific constants. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.58291

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

Low-frequency noise has been studied inAl0.15Ga0.85N/GaNhigh electron mobility transistors grown on sapphire substrates by metal organic vapor phase epitaxy. By varying the gate voltage(VGS),three regions of drain 1/f noise were clearly established underVDS=50&hthinsp;mVbiasing. FromVGS=−4&hthinsp;V(pinch-off) to 0 V, noise power generated at the transistor channel, which scales with device area, dominates. A Hooge parameter as low as5×10−4was found atVGS=0&hthinsp;V.ForVGS>0&hthinsp;V,noise power density does not depend on device area. At low gate voltages noise is generated at the ohmic contacts, whereas forVGS>1.25&hthinsp;Vit is related to the gate leakage Schottky current. A random telegraph signal (RTS) excess noise originating in the ohmic contacts has also been investigated by using a temperature analysis. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.58285

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

Low-frequency noise (1 Hz–100 KHz) measurements have been performed on twelve n-MOSFETs with 5 &mgr;m width and 0.23–10 &mgr;m varying lengths. TheSi-SiO2interface state density computed from the noise measurements using the long-channel McWhorter Theory was found to be about two orders of magnitude lower than that measured through the I-V characteristics using the sub-threshold swing. This is most likely due to the fact that I-V characteristics probe to the fast interface states while noise is affected by the slower states further into the oxide. This effect might be compounded by the thinness of the oxide layer. The drain current power spectral density was found to vary inversely with effective channel length,SI∝Leff−3at low drain voltages, but showed a higher dependence,SI∝Leff−4,at higher drain voltage values for short channel devices. This is believed to be due to the channel shortening effect caused by the depletion region of the drain and the additional g-r noise generated by the same depletion region. Three H-SPICE models have been implemented to analyze the noise. Limitations of these models for short channel devices are discussed. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.58292

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

We report low frequency noise measurements on Mg-doped GaN. The bulk sample studied was grown by MOCVD on a sapphire substrate. Ohmic contacts were made by annealing a Pt/Au metallization to a sample with volume1&hthinsp;cm×0.3&hthinsp;cm×2&hthinsp;&mgr;m.The noise properties were studied at 300K to 400K for a wide range of frequencies (1 Hz–100 kHz). A constant current was applied to the sample and the noise voltage between two other contacts was measured using a lock-in amplifier. Generation recombination (g-r) noise and 1/f noise are observed for temperatures above 300 K. The generation-recombination noise is related to a trap level with activation energy of 183 meV, coinciding with the Mg level in the bulk region. The spectral density of the noise fluctuations typically varied from10−11&hthinsp;V2/Hzat 1 Hz to10−16&hthinsp;V2/Hzfor 100 kHz. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.58293

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

This paper investigates the emission and capture kinetics of random telegraph signals (RTS) in MOSFETs. A modified two-step approach is proposed which includes the capture of a carrier by trap located at theSi-SiO2interface, followed by a tunneling process of the trapped carrier between the interface trap and a trap located in theSiO2layer. In this case the quantum transitions represent a primary process which involves three basic states. In some cases this can be approximated by a two states g-r processX2(t),which coincides with a secondary process Y(t) representing current modulation. It is shown that by this model a quadratic dependence of the capture rate on the drain current can be explained, provided that the quasi-Fermi level at the surface is below the interface trap level. From the presented model the ratio of interface trap cross-section and oxide trap cross-section determines the capture and emission time. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.58294

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

Low frequency noise characteristics of a high voltage, high performance complementary polysilicon emitter (PE) bipolar transistors are described. The influence of the base biasing resistance, emitter geometry, and temperature on the noise spectra are discussed. The npn transistors studied exhibited 1/f and shot noise, but the pnp transistors, are characterized by significant generation-recombination noise contributions to the total noise. For both types of transistors, the measured output noise is determined primarily by the noise sources in the polysilicon-monosilicon interface. The level of the 1/f noise is proportional to the square of the base current both for npn and pnp transistors. The contribution of the 1/f noise in the collector current is also estimated. The area dependence of 1/f noise in both types of transistors, as well as other npn bipolar transistors are presented. Low frequency noise in a low voltage (5V and 10V), high performance npn transistor technology are also presented. For these transistors, the effect of different base implant and rapid thermal annealing conditions, polysilicon emitter thicknesses, and surface etching conditions on the noise magnitude were studied, and these results are also reported. Finally, results pointing to the possible origin of 1/f noise in PE BJTs are presented. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.58295

出版商:AIP    

年代:1999

数据来源: AIP