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The 1/f noise performance of advanced complementary bipolar process from united technologies (ACUTE) is presented as a function of total dose, device geometry, and polarity as well as bias condition during irradiation. ACUTE's noise performance is also compared to noise from devices built on a standard bipolar process. The measured noise spectrum is expressed in terms of Hooge's constant-/spl alpha//sub H/ which normalizes the "noisiness" of the device to its geometry and doping profiles and therefore allows one to compare different structures. The results indicate a significant radiation tolerance and superior low noise of ACUTE process as compared with standard bipolar technology.

A macro model of the 6.2-V 1N5920B Zener diode which very accurately represents the measured characteristics both in the DC and AC domain is presented. For users who do not have access to optimization software, the model can still be easily customised for other Zener diodes by replacing the emission coefficients (N), saturation currents (Is) and series resistance (Rs) under forward and reverse bias. One would also need to modify the temperature coefficient and measure the capacitance (CIO) at V/sub d/=0 V bias, to have a functional model of the Zener diode. However, there is no easy technique to extract the TT parameter without going through an extraction process. Therefore, without modification to the T1 parameter, one has to be careful when using the customized model for switching applications. >

The numerically simulated performances of two subcell tandem and three subcell triple amorphous silicon-based, multijunction solar cells are compared. The current-voltage characteristics are calculated using a simulation program which allows for accurate determination of single-junction or multijunction cell response under monochromatic or global AM1.5 spectrum. The validity of the solar cell model is confirmed by the excellent agreement between the simulated and measured characteristics of in-house fabricated 13.0% tandem and 13.7% triple cells with a minimum optical bandgap of 1.4 eV. It is shown that if an even narrower bandgap material of 1.3 eV were used, the triple junction device would exceed the tandem by over 1% under global AM1.5 (14.2% versus 13.2%). Assuming that both cells absorb the same amount of light, this difference is mainly due to the weaker electric fields in the double-junction cell in which the individual cell thicknesses are larger. >

A simulation program for amorphous-silicon-based p-i-n solar cells which allows for accurate calculation of single-junction or multijunction cell response under monochromatic or global AM1.5 illumination is discussed. The device model is based on a complete set of Poisson and current continuity equations describing the amorphous intrinsic and microcrystalline or amorphous n/sup +/ and p/sup +/ contacts. It predicts solar cell behavior with uniform and nonuniform optical (mobility) bandgaps, spatially dependent doping densities, and various layer thicknesses, as demonstrated by the very good agreement between the experimental and simulated current-voltage characteristics of single cells, with the bandgaps in the range of 1.75 to 1.47 eV. The material parameters used in the simulation have been obtained from experimental results reported in the literature. The possibility of obtaining higher efficiencies using novel cell designs has also been investigated. Calculations have been carried out on cell structures in which the bandgap of the intrinsic layer is profiled to help hole transport. The most efficient structure, also confirmed by recent experimental data, incorporates normal profiling throughout the bulk of the intrinsic layer with a thin graded buffer at the p/sup +/-intrinsic junction. >

The dilemma facing the semiconductor company supplying the wireless markets is not trivial. Deciding what technology to choose for commercial applications where the price, time to market and the performance of the chip, makes or breaks the product and sometimes a company as well. This paper attempts to analyze these issues from the perspective of a fables design house. It reviews the technical aspects of the processes that are provided by a number of foundries but sometimes are difficult to compare when BiCMOS and RFCMOS compete for the same application. The paper tries to establish a procedure where a number of figures of merit are compared against each other. Besides the technical aspects also the economical considerations are discussed. Ultimately, it is intended to help the designer/decision maker to decide what process to choose for the wireless or mixed signal and/or system on a chip designs.

Differential transmission lines (DTL) can be synthesized as a chain of identical 4-Port unit cells (UC). These DTL are interesting to use for either matching the circuits or for realizing small resonators in filters or oscillators. One very interesting aspect is the tunability of such a transmission line. Tunability means the ability to tune the electrical length and the characteristic impedance by applying appropriate voltage. In this paper, we introduce a new method to realize the tunability of these transmission lines thru magnetic coupling. This tunable Periodical DTL (PDTL) provides highly interesting applications for silicon MMICs.

The 1/f noise performance of Advanced Complementary Bipolar Process from United Technologies (ACUTE) is presented as a function of a total dose, device geometry and polarity as well as bias condition during irradiation. The data shows a significant radiation tolerance and superior low noise as compared with a standard bipolar processes.

The exact location and magnitude of 1/f noise sources in silicon transistors was determined by a simple technique described in a previous publication [1]. This method, implementing the natural feedback action of actively biased devices, can generally be utilized to locate low-frequency noise generators in bipolar transistors. This paper presents measurements done on two silicon p+-n-p transistors. In the first device, the dominant noise source is due to generation-recombination, whereas the other less noisy device exhibits mainly diffusion noise.

For the first time flicker noise in the collector of p + - n-p Ge82-185 silicon bipolar transistors is observed unobstructed by the amplified base noise sources. The 1/ f spectrum from the collector is attributed to the scattering of carriers during diffusion through the forward biased base rather than their recombination. Both agreement and disagreement is found between α Hp and α Hn as given by the theory of acoustic phonon scattering and our experimental Hooge's constants. No evidence is found to indicate either Umklapp or intervalley scattering as possible sources for the 1/ƒ noise.

The experimental values of α H of n -channel Si-JFETs are compared with recent calculations by Kousik for the intervalley and acoustic phonon scattering. The average value of α H due to these two processes is only a factor 3–4 larger than the empirical date indicates. However, the best agreement with the experiment comes from the semi-heuristic formula for Umklapp scattering, modified by the temperature dependent factor[1]. Incorporation of U-type processes into the numerical model of Kousik and van Vliet for the Hooge parameter could possibly reduce the present difference even further.

A description is given of a simulation program for multijunction a-Si alloy solar cells which allows for the accurate calculation of double and triple cell-response under global AM1.5 illumination. Each device is described by a complete set of Poisson and current continuity equations covering the amorphous intrinsic and highly conductive microcrystalline contacts. The program allows for optical and mobility bandgap variation as well as for spatial variation in doping densities, device thicknesses, and spectrum modification. Excellent agreement between experimental and simulated results for a dual bandgap triple solar cell confirms the reliability of the model. To achieve even higher efficiencies a novel triple-cell structure with lower-bandgap material is proposed. This approach is viable due to the bandgap profiling, which compensates for the poorer transport properties of narrower-bandgap alloys. >

The authors have developed an amorphous silicon alloy-based solar cell with a novel structure. Computer simulation studies show that for a given short-circuit current, it is possible to obtain a higher open-circuit voltage and fill factor than in a conventional cell design. For a nominal 1.5 eV a-SiGe alloy, the fill factor under red illumination can be improved from 0.55 to 0.64 for the same short-circuit current. Experimental cell structures confirm the theoretical prediction. The novel cell design shows a considerable improvement in efficiency. Dynamic internal collection efficiency measurements show reduced recombination in these cells, which gives rise to the observed higher fill factors. Incorporation of this structure in the bottom cell of a triple device has resulted in the achievement of 13.7% efficiency under global AM1.5 illumination. >