Development of inorganic/organic-based diluted magnetic semiconductors for spin-polarized transistors

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There is no doubt that progress in the semiconductor electronics has impacted immensely on our standard of living in the past 30 years. This rapid growth has been driven by scaling a variety of electronic devices. However, it was recently predicted that traditional semiconductor electronics will face fundamental limitations in near future. When the device scaling goes below around 10 nm (65 nm at present), a reliable information processing is known to be impossible due to the quantum behavior of electrons. To overcome this problem and attain further progress, spin-electronics (or spintronics) utilizing both spin-dependent and charge-dependent electric currents has been intensively exploited as a promising alternative to the semiconductor technology relying only on the binary states of electric current (bit of 1 or 0). I am proposing this research program to produce new ferromagnetic semiconductors which is a key element in spin-electronics. The spin is an intrinsic property of electrons which can be manifested as two distinguishable magnetic-energy states (spin-up and spin-down). The conventional semiconductor-based electronics have utilized only the charge degree of freedom (positive holes and negative electrons) without considering the spin properties of charge carriers because ferromagnetism is absent in currently available semiconducting materials. Therefore spintronics technology requires new semiconductors which show ferromagnetic behavior and thus allow a current of spin-polarized electrons to be generated and controlled, and preserve the spin-coherence over long time and distance in an existing semiconductor structure. The incorporation of magnetism into organic-and inorganic-based semiconducting materials will be attempted using the magnetic-impurity doping method. This work on ferromagnetic semiconductors and their abilities to transport the spin-polarized electrons will facilitate the realization of future spintronic devices, including spin-transistors, magnetic memory, logic-circuits working both in magnetic and electric fields.