Microelectronics Engineering

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Browsing Microelectronics Engineering by Author "Ermias, Tewabe"

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    Analysis of The Functional Variation of Cascaded Amplifier When Replaced with Their Spintronics Equivalents
    (Addis Ababa University, 2019-07) Ermias, Tewabe; Getachew, Alemu (PhD)
    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.