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A NUMERICAL STUDY OF THE DEPENDENCE OF UNITY GAIN BANDWIDTH fT ON POLYSILICON EMITTER IN BIPOLAR TRANSISTORS

A NUMERICAL STUDY OF THE DEPENDENCE OF UNITY GAIN BANDWIDTH fT ON POLYSILICON EMITTER IN BIPOLAR... The effects of polysilicon emitter on the high frequency performance of bipolar transistors have been investigated numerically. The presence of polysilicon grain boundaries was found to slow down the response of the device. This resulted in a lower fT for polysilicon emitter bipolar transistors with a clean polysilicon monocrystalline silicon interface compared to conventional transistors with an identical emitterbase junction depth. The interfacial oxide layer that could exist at the polysiliconmonocrystalline silicon interface can, depending on the relative thickness of the polysilicon and monocrystalline silicon emitter regions, either improve or deteriorate the high frequency performance of the device. For a monocrystalline silicon emitter region that is much thinner than the polysilicon emitter region, the lower the tunnelling probability of the interfacial oxide layer the better is the improvement in fT. However, if the thickness of the monocrystalline silicon emitter region is made larger with respect to the polysilicon emitter region, the converse can be true. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png COMPEL: Theinternational Journal for Computation and Mathematics in Electrical and Electronic Engineering Emerald Publishing

A NUMERICAL STUDY OF THE DEPENDENCE OF UNITY GAIN BANDWIDTH fT ON POLYSILICON EMITTER IN BIPOLAR TRANSISTORS

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Publisher
Emerald Publishing
Copyright
Copyright © Emerald Group Publishing Limited
ISSN
0332-1649
DOI
10.1108/eb051730
Publisher site
See Article on Publisher Site

Abstract

The effects of polysilicon emitter on the high frequency performance of bipolar transistors have been investigated numerically. The presence of polysilicon grain boundaries was found to slow down the response of the device. This resulted in a lower fT for polysilicon emitter bipolar transistors with a clean polysilicon monocrystalline silicon interface compared to conventional transistors with an identical emitterbase junction depth. The interfacial oxide layer that could exist at the polysiliconmonocrystalline silicon interface can, depending on the relative thickness of the polysilicon and monocrystalline silicon emitter regions, either improve or deteriorate the high frequency performance of the device. For a monocrystalline silicon emitter region that is much thinner than the polysilicon emitter region, the lower the tunnelling probability of the interfacial oxide layer the better is the improvement in fT. However, if the thickness of the monocrystalline silicon emitter region is made larger with respect to the polysilicon emitter region, the converse can be true.

Journal

COMPEL: Theinternational Journal for Computation and Mathematics in Electrical and Electronic EngineeringEmerald Publishing

Published: Apr 1, 1991

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