Browse Prior Art Database

Multistate Bipolar Transistor

IP.com Disclosure Number: IPCOM000120974D
Original Publication Date: 1991-Jul-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 3 page(s) / 76K

Publishing Venue

IBM

Related People

Tiwari, S: AUTHOR

Abstract

A bipolar transistor with midgap levels in sufficiently large density to allow impurity band conduction is proposed as a method for making a three-terminal device that can be used to make a transistor with multiple conduction states. Such a device can be used as a multistate switch. The device can also be used for low quiescent power applications similar to complementary FET structures. The device also exhibits negative resistance which can be utilized for microwave applications at high frequencies.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 67% of the total text.

Multistate Bipolar Transistor

      A bipolar transistor with midgap levels in sufficiently
large density to allow impurity band conduction is proposed as a
method for making a three-terminal device that can be used to make a
transistor with multiple conduction states. Such a device can be used
as a multistate switch.  The device can also be used for low
quiescent power applications similar to complementary FET structures.
The device also exhibits negative resistance which can be utilized
for microwave applications at high frequencies.

      Fig. 1 shows an energy band diagram through the emitter (E),
base (B) and collector (C) to illustrate the concept of the device as
a modification to an npn bipolar transistor. Donor-like traps ET
allow conduction at biases where electrons can tunnel from the
emitter to impurity band.  The trap density is less than the acceptor
density, but is sufficient to form the band and to allow conduction
through mechanisms, such as hopping.  At the bias where such
tunneling takes place, Vt, the transistor exhibits conduction; at
lower and higher biases it shows little conduction, as shown in Fig.
2.  Additional states can be obtained for this type of device by
introducing midgap impurities, ET, at different several discrete
energies, ET1, ET2, etc.  The base can be heavily doped and, thus,
thin, without causing increased base resistance.  Heterostructures
can be used to allow an increase in base without causing increased
base resist...