Direct growth of β-FeSi2 nanowires with infrared emission, ferromagnetism at room temperature and high magnetoresistance via a spontaneous chemical reaction method

100學年度研究獎補助論文[[abstract]]Self-catalyzed β-FeSi2 nanowires with a high aspect ratio have been synthesized by a spontaneous chemical vapor transport and reaction method. The as-synthesized single-crystalline β-FeSi2 nanowires exhibit photoluminescence at a wavelength of 1.54 μm, which is suitable for Si-based optical communication, at room temperature. The conductivity of a single-stem β-FeSi2 nanowire was found to increase with decreasing diameter. The room temperature ferromagnetism and high magnetoresistance performance of 6% at 200 K indicates that β-FeSi2 nanowires are potentially applicable for spintronic nanodevices.[[notice]]補正完畢[[incitationindex]]SCI[[booktype]]紙本[[booktype]]電子

Formation and Device Application of Ge Nanowire Heterostructures via Rapid Thermal Annealing

We reviewed the formation of Ge nanowire heterostructure and its field-effect characteristics by a controlled reaction between a single-crystalline Ge nanowire and Ni contact pads using a facile rapid thermal annealing process. Scanning electron microscopy and transmission electron microscopy demonstrated a wide temperature range of 400~500°C to convert the Ge nanowire to a single-crystalline Ni2Ge/Ge/Ni2Ge nanowire heterostructure with atomically sharp interfaces. More importantly, we studied the effect of oxide confinement during the formation of nickel germanides in a Ge nanowire. In contrast to the formation of Ni2Ge/Ge/Ni2Ge nanowire heterostructures, a segment of high-quality epitaxial NiGe was formed between Ni2Ge with the confinement of Al2O3 during annealing. A twisted epitaxial growth mode was observed in both two Ge nanowire heterostructures to accommodate the large lattice mismatch in the NixGe/Ge interface. Moreover, we have demonstrated field-effect transistors using the nickel germanide regions as source/drain contacts to the Ge nanowire channel. Our Ge nanowire transistors have shown a high-performance p-type behavior with a high on/off ratio of 105 and a field-effect hole mobility of 210 cm2/Vs, which showed a significant improvement compared with that from unreacted Ge nanowire transistors

Silicon Wafers with Facet-Dependent Electrical Conductivity Properties.

By breaking intrinsic Si (100) and (111) wafers to expose sharp {111} and {112} facets, electrical conductivity measurements on single and different silicon crystal faces were performed through contacts with two tungsten probes. While Si {100} and {110} faces are barely conductive at low applied voltages, as expected, the Si {112} surface is highly conductive and Si {111} surface also shows good conductivity. Asymmetrical I-V curves have been recorded for the {111}/{112}, {111}/{110}, and {112}/{110} facet combinations because of different degrees of conduction band bending at these crystal surfaces presenting different barrier heights to current flow. In particular, the {111}/{110} and {112}/{110} facet combinations give I-V curves resembling those of p-n junctions, suggesting a novel field effect transistor design is possible capitalizing on the pronounced facet-dependent electrical conductivity properties of silicon

Advanced Room Temperature Single-Electron Transistor of a Germanium Nanochain with Two and Multitunnel Junctions

International audienceThe single-electron transistor (SET) has tremendous importance in the microelectronic industry on account of low-power consumption, an ultrasmall size, and a large integration prospect. The key challenge is to resolve the fabrication issues of a SET to realize a mechanically steady device with reproducible and controllable transport characteristics that operate at room temperature. Herein, we report on the realization of robust and well-controlled SET devices with at least two junctions and multijunctions using an advanced nanochain (NC) architecture of germanium nanoparticles rooted by a germanium oxide ropeway. These two-junction and multitunneling-junction (MTJ) SET devices exhibit an ideal Coulomb staircase behavior of single-electron charge transfer at room temperature and obeyed the theoretical path of increasing threshold voltage with the number of tunnel junctions. This Coulomb transistor prospects magnificent rewards of room-temperature operation, periodic Coulomb oscillations, well-controlled threshold voltage and large on/off ratios and have the potential to modernize the random access memory and digital data storage technologies

Advanced Room Temperature Single-Electron Transistor of a Germanium Nanochain with Two and Multitunnel Junctions

International audienc