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Using High Tc Superconductive Oxides As Emitter Contacts for High-Gain, High-Speed Bipolar Transistors And Other Devices At Liquid Nitrogen Temperatures

IP.com Disclosure Number: IPCOM000100968D
Original Publication Date: 1990-Jun-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 59K

Publishing Venue

IBM

Related People

Arienzo, M: AUTHOR

Abstract

Disclosed is a new contacting method to bipolar devices emitters, able to minimize base current while providing low resistance.

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Using High Tc Superconductive Oxides As Emitter Contacts for High-Gain, High-Speed Bipolar Transistors And Other Devices At Liquid Nitrogen Temperatures

       Disclosed is a new contacting method to bipolar devices
emitters, able to minimize base current while providing low
resistance.

      High Tc superconductive oxides recently discovered behave as
zero resistance metals below critical temperature and critical
current.  Bipolar transistors, on the other hand, need a low
resistance emitter contact that is also capable of minimizing the
base current.  At room temperature it has been found that polysilicon
as an emitter contact provides a good electrical contact, with low
emitter resistance, and minimizes the base current with respect to
the metal-contacted case. At liquid nitrogen this effect decreases
since the properties of polysilicon (in particular, resistance)
degrade with T.  Since the new superconductors are oxides, they have
a large bandgap (difference between the conduction band and the
valence band), with the Fermi level located well into either the
conduction or, as it has been found more often, into the valence
band.  In Figs. 1 and 2, two such cases are depicted contacting
either an n-type emitter or a p-type emitter (PNP complementary
case).  In the case of Fig. 1, there will be a small barrier for
electrons (reduced at liquid nitrogen) and a larger one for holes.
If the n-type is the emitter of a bipolar transistor, holes injected
from the ba...