Supported by experiment, we establish the following for the current flow across the epitaxial collector layer of a bipolar transistor biased at the onset of base-widening effects. The flow is one-dimensional only for large collector-base voltages, when it is space-charge limited and velocity saturated. As the collector-base voltage is lowered and the device enters quasi-saturation, the flow spreads progressively. The variation of the collector current with collector-base voltage, taking into account current spreading effects, is well modeled by a simple saturating exponential function with physically based constants. © 2003 Elsevier Science Ltd. All rights reserved.

Shreepad Karmalkar

Department of Electrical Engineering

Electric currents

Electric potential

ELECTRIC SPACE CHARGE

COLLECTOR CURRENT

Bipolar transistors

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IIT Madras

On the bipolar transistor collector current at the onset of base-widening as a function of the collector–base voltage

Solid-State Electronics

Building upon our recent work (IEEE Electron Device Lett., vol. 26, pp. 909-912, Dec., 2005), we present simple and continuous closed-form models for several rectangular and circular spreading resistance geometries encountered in electrical/thermal design of devices and integrated circuits. The resistance geometries considered involve current/heat flow between parallel contacts of rectangular or circular shape and concentric or eccentric nature, between a horizontal and a vertical stripe, and between a horizontal circular contact and a surrounding vertical cylindrical contact. The modeling procedure involves normalization of the spreading resistance with respect to its value under 1-D flow conditions, followed by a curve-fit of the variation of this normalized resistance with contact area in terms of physical parameters. The resistance models may also be used to estimate the reciprocal of capacitance of similar insulator-electrode geometries, by replacing the resistivity by the reciprocal of the insulator permittivity. © 2007 IEEE.

IEEE Transactions on Electron Devices

Compact models of spreading resistances for electrical/thermal design of devices and ICs

Computer-Aided Design of Analog Integrated Circuits and Systems

HighFrequency Distortion Analysis of Analog Integrated Circuits

Physics of Semiconductor Devices

Modeling of the on-resistance of LDMOS, VDMOS, and VMOS power transistors

Journal of Business Communication

Book Reviews : Good Communication--What Every Manager Should Need to Know. John Hargreaves. New York; John Wiley and Sons, 1977, 116 pages

A unified approach to the base widening mechanisms in bipolar transistors

On the bipolar transistor collector current at the onset of base-widening as a function of the collector-base voltage

Journal	Solid-State Electronics
ISSN	00381101
Open Access	No