Quantum Transport And Device Design Of Organic-Inorganic Hybrid Molecules

Molecular electronics is the electronics of molecular level investigations. Its goal is to use single molecules, super molecules and molecular clusters instead of solid electronic components such as Si-based semiconductor transistors to assemble logical circuits and even computers. Because of conventional Si-based electronics devices continual approaching physics and size limit, the investigations of molecular electronics and spintronics attract much study interesting due to that they can conquer there difficult which Si-based electronics face. Research filed of molecular electronics involve the synthesis of variety molecular electronic devices, performance testing and how assemble them to realize certain logical functions. People anticipate that the next generation nano electronics involved molecular electronics will exceed CMOS technology and approach novel device paradigms which base fantastic nano materials such as molecules or the novel quantum transport mechanism which use spin current instead of charge current. Spintronics is the research how to control and manipulate the degree of spin in the solid systems, it focus on the spin-polarization and spin current quantum transport mechanisms. Compared with conventional electronics which only consider charge degree without spin degree, the spintronics devices have the advantages of high density, low power consumption and sensitive and have giant potential applications in future. Magnetic tunneling junctions and giant magnetoresistance devices have been applicated to the drive storage and read head respectively, which have dozens billion production value in the world each year.My investigations focus on three aspects in the following:First, I use grahene nanoribbons and other organic molecules to design and construct molecular devices such as diodes, rectifiers and filed effect transistors, etc and investigate the transport properties using first-principles calculations of Nonequilibrium Green's Function combining density functional theory approach. The investigations emphasize the mechanism of filed effect, rectification effect and negative differential resistance, which propose the theoretical and experimental elements for fabrications of molecular electronics devices. Second, I study some low-dimensional magnetic materials for providing the theoretical and experimental elements for fabrications of low-dimensional spintronics device. Low-dimensional spintronics is the interdiscipline which combines the advantages of nano electronics and spintronics. My calculations find that the transition metal atoms doped gold clusters with thiol-passivation have the function of hydrogen storage. My investigations also find that the one-dimensional half-metals constructed by noble metal and transition metal. To my surprise, the half-metals are all composed by metal atoms. Third, I use the transition metal doped boron nitrogen nanotubes to construct atom-level smooth one-dimensional magnetic tunnel junctions with high magnetoresistance. I also construct the hexagonal Co/BN/Co magnetic tunneling junctions with hexagonal Co and white graphite. Besides the high magnetoresistance, We also find that the induce magnetic moments of BN barrier have significant impacts on the magnetoresistance.