Room-Temperature Ferromagnetism of Diluted Magnetic Semiconductor Nanowires and the Nanotransistor Fabrication
Advanced Materials Research Institute,
Diluted Magnetic Semiconductors (DMS) are among the most promising candidates for spintronics, since they provide much better lattice and conductivity match compared with ferromagnetic metals as used for spin-polarized carrier sources. Doping ZnO nanostructures by one or two of dopants is a feasible strategy to achieve room-temperature ferromagnetic ordering or optimize the magnetic properties. In this talk, transition-metal (Mn and Co) doped well-aligned ZnO nanowire arrays and FeCo-codoped ZnO nanorods with room temperature ferromagnetic ordering, synthesized by chemical vapor deposition (CVD) and pulsed laser deposition methods, will be presented. The as-synthesized ZnO (Mn and Co) nanowires and FeCo-codoped nanorods were characterized by X-Ray diffractometer, field emission scanning electron microscopy (FESEM) and transmission electron microscopy (FETEM). The nanowires and nanorods are grown along the c-axis with single crystalline structure. Defects were observed in the nanowire arrays because of the substitution of Zn by Mn and Co atoms. Electron energy X-ray dispersive (EDS) analysis and electron energy loss spectroscopy (EELS) clearly showed that Mn, Co, and Fe were successfully doped in the ZnO nanowire arrays. Ferromagnetic ordering of the as-synthesized nanowires and nanorods was observed at room temperature by superconducting quantum interference device (SQUID) and electron paramagnetic resonance (EPR) spectra measurement. The fabrication of spintronic nanotransistors will also be discussed.