Showing papers on "Mobility model published in 1989"

A new approach to verify and derive a transverse-field-dependent mobility model for electrons in MOS inversion layers

Abstract: A modeling approach is described that extracts the functional dependence of carrier mobility on local transverse and longitudinal fields, channel doping, fixed interface charge, and temperature in MOS inversion and accumulation layers directly from the experimentally measured effective (or average) mobility. This approach does not require a priori detailed knowledge of the experimental variation of mobility within the inversion or accumulation layer, and it can be used to evaluate the validity of other models described in the literature. Also, an improved transverse-field dependent mobility model is presented for electrons in MOS inversion layers that was developed using this new modeling approach. This model has been implemented in the PISCES 2-D device simulation program. Comparisons of the calculated versus measured data show excellent agreement for I/sub D/-V/sub G/ and I/sub D/-V/sub D/ curves for devices with L/sub eff/=0.5 to 1.2 mu m. >

Universality of mobility-gate field characteristics of electrons in the inversion charge layer and its application in MOSFET modeling

Abstract: A mobility curve for electrons in a MOSFET inversion charge layer is determined from measured drain current of transistors produced by a wide range of MOS technologies. A comparison between this mobility curve and previously published results shows that a truly universal mobility curve does not exist and only local universal mobility curves can be expected, i.e. unique mobility curves which are valid over a finite range of MOS technologies and/or over a particular set of fabrication facilities. The curve's basic characteristic of being technology-independent over a wide range of process variation points out the potential of using such a local universal mobility curve as a powerful basis for developing predictive device modeling tools. This potential is demonstrated for an analytical MOSFET model and a two-dimensional device simulator where the mobility models have the general characteristics of experiment-based local universal mobility curves. >

Lunar Surface Mobility Studies, Past and Future

Abstract: : WES efforts contributed to selection of the metal-elastic wheels successfully used on the Lunar Roving Vehicle (LRV) and produced a quantitative description of the high-level mobility capabilities of a concept tracked running gear proposed for future US lunar surface applications (the Elastic Loop Mobility System, or ELMS). This paper reviews highlights of those Apollo-era studies--first, the determination and quantitative characterization of two terrestrial soils each successfully processed to provide a lunar soil simulant (LSS); then, the analysis of results from mobility tests conducted in LSS with several candidate LRV wheels and with several versions of the ELMS. The paper then describes capabilities developed since Apollo for use today in analyzing the mobility and soil-working potential of future US LRV's. These capabilities include judicious application of soil-running gear dimensional analysis relations, plus the use of computerized models to be modified from terrestrial to lunar applications for predicting vehicle mobility and bulldozer working capability (e.g., the Army Mobility Model and the Push-It Model, respectively). Future studies of lunar surface vehicle mobility capabilities must profit from two major lessons learned from Apollo--i.e., how to process and quantitatively describe LSS, and to appreciate that physical testing in LSS of proposed running gears and vehicles is a necessary part of lunar vehicle mobility studies.

The Mobility Model in MINIMOS

Abstract: Several authors have shown that the dependence of the mobility on the electric field perpendicular to the gate oxide is described by a "universal curve" if an effective normal electric field is used. In this paper we show that the MINIMOS-4 local mobility model agrees very well with these empirical data over the whole range of electric fields. The numerical extraction method for determining the effective mobility and effective field are given.

Improved physical modeling of submicron MOSFETs based on parameter extraction using 2-D simulation

Abstract: Hot electron effects for n-channel submicron MOSFET devices have been analyzed on the basis of accurate physical models. The PISCES-Monte Carlo scheme is implemented to calculate impact ionization coefficients and predict accurately the generation of electron-hole pairs. The coupling scheme also provides important physical parameters and constants for developing substrate and gate current models as well as an improved mobility model, especially for high drain and gate bias conditions. The analytical models for impact ionization, thermionic emission and mobility are incorporated into the PISCES program and give accurate predictions compared with experimental results. These models predict the peak and saturated transconductance curves for the high drain voltage of LDD MOSFET devices. >

Design and implementation of channel mobility measurement modules

Abstract: Low-field majority carrier channel mobility profiles are determined by combining C-V and channel conductance measurements. The measurements can be used to determine majority carrier channel mobility profiles. The C-V data can also be used for the determination of doping profiles. The theory, the design of the test structures, and the measurement techniques are discussed. Experimental results are presented for a bipolar and a BiMOS process. In the BiMOS process, a deviation from existing mobility models was found. >

On the accuracy of a particular implementation of the Shannon-Buehler method (MOSFET mobility models)

Abstract: The accuracy of the constant I/sub DS/-V/sub DS/ version of the Shannon-Buehler method is considered. The variation of the effective mobility with gate voltage and substrate bias results in the difference between the measured and actual channel impurity profiles. General expressions that allow one to compute correction factors using different MOSFET mobility models are derived. General results are illustrated by considering two commonly used mobility models. >