Diluted magnetic semiconductor for spin FET application

Traditional CMOS has been the mainstream electron devices for over half century. As the scaling becomes more difficult as anticipated by the International Technology Roadmap of Semiconductors (ITRS), alternate devices with high functionality and low power dissipation are needed. Spin based device offers potential to increase functionality by combining the logic and memory functions into one unit. Thus, spintronic devices are important.;It has been observed that when current flows from a ferromagnetic into an ordinary metal, electrons retain their spin alignment, and hence the spins aligned along a magnetic field can be transported just like charges [1]. This concept has resulted in several attempts to fabricate the spin transistors that exploit the spin dependent transport of charge carriers in order to yield a device with high spin current gain and high magnetic sensitivity. Like an electronic transistor with gain, Nikonov and Bourianoff [1] postulate that a small base current with a small spin polarization can stimulate a large spin polarization in the collector output current. The spin gain is achieved by first biasing the base to produce a sufficiently high hole concentration for ferromagnetic transition, and then by injecting a small spin-polarized control current, which acts as a stimulator to break the random orientation of the spins and to induce spontaneous magnetization in the DMS base.;In order to realize the spin FETs, it is essential to achieve efficient spin injection and detection in semiconductor or diluted magnetic semiconductor (DMS) channel. A diluted magnetic semiconductor (DMS) cell is fabricated by Mn implantation into Ge substrates with nanoscale pattern using diblock copolymer pattern and MBE growth of MnGe on Si substrates. Structure and magnetic properties are investigated by TEM (Transmission Electron Microscopy) and SQUID (Superconducting Quantum Interference Device), respectively.;Efficiently injecting spin polarized electrons from ferromagnetic materials (FM) into semiconductor (SC) has been one of the major challenges in spintronics. FM/oxide/SC structure is considered as a good candidate for spin injection or detection because the tunnel contact between FM and SC might be ideal for solving the conductivity mismatch problem. In this study, spin injection and detection in Ge and MnGe is investigated. *Please refer to dissertation for footnotes.