Fully engineered homoepitaxial zinc oxide nanopillar array for near-surface light wave manipulation

We report accurate light wave manipulation by means of an inverse designed homoepitaxial ZnO nanopillar array. Our proof-of-concept structure was optimized for focusing a near-surface light beam which propagates in a free-space parallel to the metal top surface. The on-purpose positioned and perpendicularly aligned vertical ZnO nanopillars were fabricated by homoepitaxial chemical growth technique. The obtained focal distance of 28 (mű)m as well as the light intensity distribution pattern was verified by three-dimensional finite-difference time-domain method. The demonstrated approach can provide inter- and intrachip optical connections in the next generation ZnO nanowire-based integrated photonic devices

Magnetic oxide semiconductors

Magnetic oxide semiconductors, oxide semiconductors doped with transition metal elements, are one of the candidates for a high Curie temperature ferromagnetic semiconductor that is important to realize semiconductor spintronics at room temperature. We review in this paper recent progress of researches on various magnetic oxide semiconductors. The magnetization, magneto-optical effect, and magneto-transport such as anomalous Hall effect are examined from viewpoint of feasibility to evaluate the ferromagnetism. The ferromagnetism of Co-doped TiO2 and transition metal-doped ZnO is discussed.Comment: 26 pages, 5 tables, 6 figure

Novel germanium-based magnetic semiconductors

The prospect of integrating electron charge and spin degrees of freedom has invigorated the field of spinpolarized electronics,‘‘spintronics’’ [1,2]. Most activities are focused on Mn-doped compounds of group III-V and II-VI families, where high quality ferromagnetic epitaxial films have been grown with Curie temperature TC reaching 110 K [3]. However, there is considerable interest in higher TC materials particularly in group IVelements, owing to their potential compatibility with current Sibased processing technology. Recent studies [4,5] show that Ge crystals doped with a transition metal element do exhibit ferromagnetism at low temperature but phase separation of dopant-rich compounds remains to be the main obstacle for achieving higher doping concentrations and producing higher TC materials. Therefore, the bottleneck for implementing spintronics continues to be the lack of materials candidates. Here we report the synthesis and properties of high quality epitaxial films of high TC magnetic semiconductors of Co and Mn-doped Ge. We show that doping with two elements can stabilize structures at higher doping concentrations than those doped with one of the elements, and that the strong interplay between structure and magnetism gives rise to novel magnetotransport phenomen

Combinatorial Study of Ni-Ti-Pt Ternary Metal Gate Electrodes on HfO\u3csub\u3e2\u3c/sub\u3e for the Advanced Gate Stack

The authors have fabricated combinatorial Ni–Ti–Pt ternary metal gate thin film libraries on HfO2 using magnetron co-sputtering to investigate flatband voltage shift (ΔVfb) , work function (Φm) , and leakage current density (JL) variations. A more negative ΔVfb is observed close to the Ti-rich corner than at the Ni- and Pt-rich corners, implying smaller Φm near the Ti-rich corners and higher Φm near the Ni- and Pt-rich corners. In addition, measured JL values can be explained consistently with the observed Φm variations. Combinatorial methodologies prove to be useful in surveying the large compositional space of ternary alloymetal gate electrode systems