Analysis of The Functional Variation of Cascaded Amplifier When Replaced with Their Spintronics Equivalents
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Date
2019-07
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Addis Ababa University
Abstract
Spintronics is a new technology that employs the spin degrees of freedom of carriers instead of
electrons’ charge for storing and processing data. Either by using spins alone or by adding the spin
degrees of freedom to the more established semiconductor technology, it is possible to enhance
the functionality of the device greatly.
In this thesis, two major things have been done. In part one, after studying literature reviews which
were done on spin transistors, magnetic bipolar transistor models are proposed, Three quite
different magnetic bipolar transistors are developed by incorporating magnetic impurities in all
three regions. And the energy band edges of semiconductor device in the presence of magnetic
impurities are calculated. In part two, the proposed spin transistors models are validated by
employing on some application areas (Cascaded amplifier). The performances of magnetic bipolar
transistors (i.e., using one of the models of spin transistors and the proposed ones) for multistage
amplifiers are analyzed. In order to simplify the equivalent circuit for AC analysis, simplified re
model for low frequency is used. And hybrid-π model is used for high frequency. Since each
parameters in re model and hybrid-π model are function of spin polarization of carriers, the
equivalent circuit models used in this thesis work quite well for spin based transistor.
In this thesis it is able to come up with quite different types of magnetic bipolar transistors in which
spin of carriers are the main controlling inputs. It is shown that the device’s parameters are function
of the spin of electrons and holes, and the injected spin electrons in the emitter and collector.
Contrary to the conventional bipolar transistor, the magnetic bipolar transistor models are capable
of controlling current amplification factor and the density of minority of carries through spins of
electrons and holes. As a result, the performances of cascaded amplifier are improved compared
to the performances of the conventional transistor.
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Keywords
spin transistor, spin, polarization of electron, magnetic bipolar transistor