Low-frequency noise in single–poly bipolar transistors at low base current density

This paper deals with the low-frequency noise of single–poly bipolar transistors (SBJT) biased at low base current density. From Gummel plots and low-frequency noise measurements performed on many SBJTs made using the same process, it is clearly demonstrated that the low-frequency noise is related to generation–recombination mechanisms (GR) that occur at the periphery of the emitter–base space charge region. A model which takes into account both the diffusion noise and the GR noise is proposed. A comparison with some measurements performed on another BiCMOS technology and with some results of the literature validates this analysis.     

Low-frequency noise in polysilicon emitter bipolar transistors

The low-frequency noise in polysilicon emitter bipolar transistors is investigated. Transistors with various geometries and various properties of the oxide layer at the monosilicon polysilicon interface are studied. The main 1/f noise source proved to be located in the oxide layer. This source causes both 1/f noise in the base current S_Ib and 1/f noise in the emitter series resistance S_re The magnitude of the 1/f noise source depends on the properties of the oxide layer. The 1/f noise is ascribed to barrier height fluctuations of the oxide layer resulting in transparency fluctuations for both minority and majority carriers in the emitter, giving rise to S_Ib and S _re respectively. It is also shown that a low transparency of the oxide layer also reduces the contribution of mobility fluctuations to S_Ib     

Low-frequency noise sources in bipolar junction transistors

Low-frequency noise measurements are made on specially fabricated silicon tetrode planar transistors. The measurements show the existence of three distinct sources of excess noise: a 1/fnoise source associated with the surface; a l/fnoise source associated with the active base region; and an anomalous burst noise source associated with the forward-biased emitter-base junction. Burst noise which is present in many transistors is a random fluctuation of the dc currents of the transistor. The terminal characteristics of these various noise sources are described and a modified noise model is presented which is useful for low-frequency noise calculations.     

Low-frequency noise in TFSOI lateral n-p-n bipolar transistors

Low-frequency (1/f) noise is characterized as a function of base current density (J_B) on thin-film-silicon-on-insulator (TFSOI) lateral bipolar transistors. In the low injection region of operation, the noise power spectral density was proportional to J_B ^1.8 for J_B<0.4 μA/μm², which suggest that the noise in these devices is primarily dominated by a uniform distribution of noise sources across the emitter-base area. However in the high current region of operation (J_B>0.4 μm²), the noise bias dependence shifts to J_B ^1.2, indicating current crowding effects, alter the contribution of noise sources near the extrinsic base link region of the device. In addition to the expected 1/f noise and shot noise, we have observed a bias dependent generation-recombination (Gm) noise source in some of the devices. This G/R noise is correlated to random-telegraph-signal (RTS) noise resulting from single trapping centers, located at or near the spacer oxide and/or the Si to SIMOX interface, which modulate the emitter-base space charge region     

Avalanche-induced 1/f noise in bipolar transistors

It has been proposed that degradation of low current hFE, as a result of avalanching the emitter-base junction of a bipolar transistor, can be attributed to an increase in surface recombination velocity within the emitter-base space-charge region. This work shows that 1/fnoise is also increased during avalanche and that this increase is consistent with a previously reported correlation between surface recombination velocity and 1/fnoise.     

Origin of 1/f noise in bipolar transistors

In planar n-p-n transistors fabricated in IC technology, the dependence of 1/fnoise on the base current density jB, the base width WB, and the emitter area FEwas measured. The power spectrumS_{iB}(f)of the base current fluctuations iBcan be represented by the empirical relationS_{iB} = const. jmin{B}max{gamma} cdot Fmin{E}max{beta} cdot wmin{B}max{-1} cdot f^{-1}where1 leq gamma leq 2and β has been found to be 1.3 or 2. The results of measurements on gate-controlled devices indicate that 1/fnoise cannot be explained by McWhorter's surface model. Therefore, a new model is proposed which assumes resistance fluctuations in the base region as the cause of 1/fnoise in bipolar transistors. The model establishes the relation forS_{iB}(f)as well as the magnitude of the coefficients β and γ.     

Bias dependence of high-frequency noise in heterojunction bipolar transistors

Hawkins' isothermal model developed to study noise in bipolar junction transistors (BJTs) is modified to investigate bias-dependent noise in heterojunction bipolar transistors (HBTs) by incorporating thermal effects. It is shown that the inclusion of thermal effects into the high-frequency noise model of HBTs is necessary as the temperature of the device may become very different from the ambient temperature, especially at high bias current. Calculation of the noise figure by including the thermal effect shows that the isothermal calculation may underestimate the noise figure at high bias current. It is observed that noise at low bias is ideality factor n dependent whereas high bias noise is insensitive to the variation of n. Moreover, the common base current gain plays a major role in the calculation of the minimum noise figure. The excellent fit obtained between the theoretical calculation and the measured data are attributed to the inclusion of the bias-dependent junction heating as well as C/sub De/ and C/sub bc/ into the present calculation.     

RTS noise in submicron SiGe epitaxial base bipolar transistors

In this paper, we report a comprehensive study of Random Telegraph Signal (RTS) noise in SiGe epitaxial base bipolar transistors. We analyse the multilevel fluctuations of base and emitter forward currents before and after reverse stress on the emitter-base junction. We show the influence of the chemical treatment preceeding polysilicon emitter deposition on noise properties. We identified that RTS noise arises from different regions in the device : the silicon/polysilicon interface if an oxidizing surface preparation is used, and the emitter periphery after stress-induced degradation. Temperature and bias dependent measurements allowed us to characterize these defects (activation energy, defect type), to analyse their impact to the low frequency noise properties of these transistors and to discuss the role of hot carrier stressing.     

Burst and low-frequency generation-recombination noise in double-heterojunction bipolar transistors

The low-frequency noise in a double-heterojunction bipolar transistor (DHBT) consisted of burst noise and generation-recombination g-r noise. The current dependence of the base burst noise with floating collector was of the form IB³and the current dependence of the collector g-r noise with HF short circuited base was as IC^3/2. The centers involved in the noise generation had an activation energy of about 0.40 eV, with an indication of a second center of lower energy in the collector noise.     

Effective recombination velocity of polysilicon contacts for bipolar transistors

The effective surface recombination velocity is determined analytically for a doped polysilicon contact to the emitter of a bipolar transistor in the presence of a thin interfacial oxide layer. Results are presented for various doping levels, oxide thicknesses and barrier heights. The analysis considers both tunnelling and thermionic emission through the interface.     

Microwave noise characterisation of poly-emitter bipolar junction transistors

The microwave noise characteristics of poly-emitter bipolar junction transistors have been evaluated in a 0.8 mu m silicon BiCMOS process, at frequencies between 1 and 5.6 GHz and for collector currents between 0.5 and 15 mA. Using a small-signal model for the poly-emitter bipolar junction transistors, very good agreement has been obtained between measurements and calculations of both noise figure (F/sub MIN/) against frequency, and F/sub MIN/ against collector current. It is found that F/sub MIN/ was 2.3 dB at 1 GHz and 8.3 dB at 5.6 GHz for a collector current of 5 mA.<>     

On the noise performance of bipolar transistors in untuned amplifiers

From a generalized approach this paper reexamines the noise performance of bipolar transistors in untuned amplifiers. New results are obtained for the upper corner frequency which fully characterize the frequency dependent noise figure curves under conditions of arbitrary and optimum source conductance termination. The effects of the collector bias current on the minimum noise figure, the optimum source conductance and the upper noise corner frequency are presented both analytically and graphically. The results also include the effects of source capacitance on noise figures. A systematic design of low-noise untuned low-pass amplifiers with desired gain-bandwidth performance can be readily achieved with the help of the results presented.     

1/f voltage noise in silicon planar bipolar transistors

Measurements on silicon planar transistors in the frequency range 1 Hz?1 kHz have shown conclusively that 1/f noise is present on the equivalent input noise-voltage generator. In some samples of transistors, correlation between the 1/f components of voltage and current noise was detected. In one sample, an estimate of the correlation coefficient was made, the result being a coefficient of approximately ?0.1.     

On the current dependence of low-frequency noise in bipolar transistors

The bias dependent characteristics of the base input flicker noise or 1/f noise current generator in bipolar transistors is examined. A simple technique is presented for the determination of the flicker noise magnitude at selected low frequencies with varying collector bias current. The results indicate that the bias dependence of the flicker noise is intimately rated to that of the input conductance parameter gπin the common-emitter configuration. Practical methods are given for the determination of the bias-independent noise parameter ρ0, which, in conjunction with the small-signal network parameters, fully characterize the device noise performance at low frequencies, ρ0, is an equivalent noise resistance representing the open-circuit flicker noise voltage at the base terminal at 1 Hz. Results of noise figure measurements on several representative commercially available devices are compared with those calculated with a knowledge of ρ0.     

Collector recombination lifetime from the quasi-saturation analysisof high-voltage bipolar transistors

A novel method of measuring the collector recombination lifetime, which is independent of emitter effects, is presented by extending the quasi-saturation analysis of high-voltage bipolar transistors to the high-current-density regime. The technique is supported by theory, and experimental results are presented on transistors fabricated with different emitter properties. This is a nondestructive method and gives the lifetime values at the current densities normally encountered when the transistor is in actual operation. The values for the collector recombination lifetime obtained by the present method are independent of the properties of the emitter region     

Junction temperature dependence of high-frequency noise inheterojunction bipolar transistors

The use of the Hawkins model, under isothermal condition, to calculate the bias dependent high frequency noise in Heterojunction Bipolar Transistors (HBTs) is questioned. The inclusion of thermal effects into the noise model of HBTs is necessary as the temperature of the device becomes progressively different from the ambient temperature with increasing bias current. Calculation of noise figure by including the thermal effects explains the experimental measurement whereas the isothermal calculation underestimates the noise figure at high bias current     

Characterization of generation–recombination noise using a physics-based device noise simulator

The implementation of generation–recombination (g–r) noise in a partial differential equation based device simulator is presented. Derived from the Shockley–Read–Hall model, the strength of each local g–r noise source is calculated based on the carrier transition rates between the conduction band, valence band, and trap states. The perturbations of these local g–r noise sources are then transmitted to the electrodes of the simulated device through scalar Green’s functions. g–r noise simulations are compared with existing measurements made on a four trap level, p-type silicon resistor. Good agreement between measured and simulated data is observed.     

Modeling of emitter-base bulk and peripheral space-charge-layer recombination currents in bipolar transistors

The bulk and surface recombination currents of the E-B space-charge layer are related through a factor XFShaving the dimensions of length. The factor XFScan be determined experimentally and is an essential parameter for modeling hFEfall-off at low collector currents.     

Temperature dependence of 1/f noise in polysilicon-emitter bipolar transistors

1/f noise was measured on polysilicon-emitter bipolar n-p-n and p-n-p transistors over a temperature range of 173K相似文献   

Theory of 1/f noise in bipolar silicon planar transistors

A theory of 1/f low-frequency noise in silicon planar transistors is developed. It relates this noise to fluctuations in base current produced by fluctuations of occupied traps in the silicon dioxide. It is shown that the theoretical relationship of noise is consistent with experiment.