摘要:

Low-frequency noise measurements are performed on classical Si bipolar transistors and on AlGaAs/GaAs heterojunction bipolar transistors (HBTs) mounted in a common-emitter configuration. Expressions for the spectral densities are derived taking into account a correlation between base and collector noise sourcesibandic. Values of emitter series resistances and of the base ideality factor are determined from these noise measurements. Then the spectral densities related toibandicas well as the cross-spectrum are extracted. In the case of classical Si transistors, the excess noise is attributed to the current noise sourceib. The effect of the base series resistance is shown on the white noise. For the HBTs, the white noise is not reached. The excess noise is attributed to the correlated current noise sourcesibandic. From the analysis of the current spectral densities with base current the increase of correlation with bias is revealed. The extracted current spectral densities provide the foundation for the calculation of the coherence function associated to base and collector currents. This coherence function is presented in part II. The shape of the curves shows correlation phenomena to be mainly related to generation-recombination components. Also in part II, the spectral densities associated with the correlated and uncorrelated part of the collector current are extracted and studied versus bias and geometry. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363930

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Low-frequency noise measurements were performed on heterojunction bipolar transistors (HBTs) and presented in part I of this article. These measurements revealed a partial correlation between base and collector noise current sources. With the help of the current spectral densities determined in part I, the coherence function is calculated and studied versus bias in this second part. Important values of the coherence function are obtained at the highest bias. Then the spectral densitiesScandSncassociated to the correlated and uncorrelated parts of the collector current noise source are extracted and analysed. All spectra exhibit excess noise. A difference in shape is clearly observed because of an important generation-recombination component occurring around 1 kHz on the correlated part only. To compare the behavior of different transistors a normalized coupling coefficient is introduced. The correlation is seen to increase with the scaling-down of devices. The investigation of the coupling coefficient with collector current density leads to hypothesis concerning the origin of the generation-recombination (g-r) components. Some components are shown to originate in the intrinsic transistor, and others in the extrinsic one, depending on frequency and type of HBT. Mainly the noise correlation is due to leakage currents and/or recombinations in the base-collector junction. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363931

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Optimization of the measurement sensitivity using closed form analytical expressions derived from an electrical equivalent circuit is carried out for microwave detected photoconductance decay system used for nondestructive carrier lifetime measurement in silicon wafers. The effect of transverse inhomogeneity in the sample conductivity on the microwave power reflection is discussed using the equivalent circuit model. The effect of lateral inhomogeneity in the sample conductivity due to local illumination by a source with a laterally varying intensity is studied using an elaborate analytical two-dimensional model. Finally, the effect of transient lateral carrier diffusion in a sample subjected to a pulsed illumination on the extracted value of the lifetime is investigated. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363932

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

By an analysis of the exchange of carriers through a semiconductor junction, a general relationship for the nonequilibrium population of the interface states in Schottky barrier diodes has been derived. Based on this relationship, an analytical expression for the ideality factor valid in the whole range of applied bias has been given. This quantity exhibits two different behaviours depending on the value of the applied bias with respect to a critical voltage. This voltage, which depends on the properties of the interfacial layer, constitutes a new parameter to complete the characterization of these junctions. A simple interpretation of the different behaviours of the ideality factor has been given in terms of the nonequilibrium charging properties of interface states, which in turn explains why apparently different approaches have given rise to similar results. Finally, the relevance of our results has been considered on the determination of the density of interface states from nonideal current-voltage characteristics and in the evaluation of the effects of the interfacial layer thickness in metal-insulator-semiconductor tunnelling diodes. ©1997 American Institute of Physics. 

ISSN:0021-8979    

DOI:10.1063/1.364305

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We provide a quantitative analysis of the Faraday cage method for determining the leakage of electric charge across the surface of insulators, and correct some inconsistencies in earlier work. We show that it is possible to distinguish between the mechanisms of surface conduction and surface charge driven flow, since in the latter case the time constant depends on the amount of the initial charge and the logarithmic decay rate slows down at long times. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363971

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

This article reports new experimental results on the continuing interface trap generation post-hot hole injection and investigates the generation mechanism. The generation post-hole injection is found to be two orders of magnitude slower than that post-irradiation and cannot be satisfactorily explained by the transportation of hydrogen species across the gate oxide. The role played by the recombination of trapped holes with free electrons is examined. There is a lack of correlation between the trapped hole removal and the interface trap creation, which is against the prediction of the trapped hole conversion model. The results indicate that the interface traps generated during and post-stress originate from two different defects. The defect responsible for post-stress generation is excited by hole injection and then converted into an interface trap if a positive gate bias is applied. It is found that generation in a poly-Si gated metal–oxide–semiconductor field effect transistor behaves differently from that in an Al-gated device. The possible causes for this difference are discussed. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363969

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

In a pair of coupled quantum dots under an external electro-magnetic field, new types of resonant absorption are caused by electron–electron interaction. Quasi-resonance between states of multiple electrons caused by electron–electron interaction can be controlled by an external electric field in the direction of coupling of quantum dots. This kind of resonance produces two types of resonant absorption of a photon, so that far-infrared absorption spectra have additional peaks. These quasi-resonant states of multiple electrons are investigated by optical transitions modulated by an external magnetic field. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363933

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Side gated silicon quantum wires of nominally uniform 60 nm/70 nm width, 40 nm height, and 4 &mgr;m/6 &mgr;m length have been fabricated in the silicon-on-insulator configuration. Measurements of the current–voltage characteristics at a temperature of 2.0 K show significant nonlinearities including a zero conductivity blockade region and conductance peaks suggestive of single electron behavior. The blockade size is significantly affected by application of a gate potential and oscillations of the blockade and wire conductivity with gate potential are also observed. These features are explained by a single electron tunneling model of a multiple island system. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363934

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We have calculated the effect of an electric field applied along the direction of carrier confinement on the scattering of excitons by free carriers in semiconducting quantum-well structures. We find that although the application of the electric field does not change the functional form of the dependence of the differential cross section on the scattering angle or the dependence of the total cross section on the incident wave vector of the free carrier, it does change the magnitude of the total cross section. For scattering of heavy hole excitons by electrons, the peak value of the total elastic cross section decreases with increasing electric field while when the exciton is scattered by heavy holes, the peak value of this cross section increases with electric field. This reduction or enhancement is negligible for narrow wells or for weak fields but there is an appreciable change in the total elastic scattering cross section for wider wells and stronger fields. We also find that the electric field also enhances the ionization cross section for the scattering of excitons by both electrons and heavy holes. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363972

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A detailed structural and morphological investigation has been carried out by conventional transmission electron microscopy, high resolution electron microscopy and nanodiffraction methods on vanadium oxide films obtained by reactive rf sputter at a high power discharge (1000 W) and different O2/Ar ratio. Electrical characterization has been also performed in controlled atmosphere in order to investigate the influence of NO2oxidizing gas on the material conductance as a function of deposition parameters. A strict relation between structure, morphology and resistance variation in controlled atmosphere has been observed. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363973

出版商:AIP    

年代:1997

数据来源: AIP