Search

Core-shell nanowires are an essential component of numerous nanoscale device concepts. In this study, germanium and silicon nanowires were synthesized bottom-up using the vapor-liquid-solid technique and successively modified with a silicon shell. The shell synthesis was studied with focus to the crystallinity but includes as well the electrical characteristics of n- and p-doped radial core-shell nanowire devices. Furthermore, the influence of certain post-annealing procedures on the crystallinity of the core-shell nanowires are discussed. We demonstrate that the crystallinity of the silicon shell can be tuned from single-crystalline to amorphous in a controlled manner, independent on a p- or n-type doping, by deliberate adjustment of the growth parameters. [ABSTRACT FROM PUBLISHER]

In this paper, we derive a quantitative model for the manipulation of superparamagnetic particles by superposition of a homogeneous magnetic field and magnetic field gradients. Our results show that by this combination, the magnitude as well as the sign of the force on a magnetic particle can be controlled. By quantitatively modeling the magnetic force on a representative superparamagnetic particle, we find that for a common lab-on-chip scenario large repulsive forces can be achieved by adding a homogeneous field perpendicular to the plane of the chip. This offers new perspectives for the on-chip manipulation of magnetic particles. As a first example, in-plane positioning of particles with an accuracy of \(\sim 1 \mu \) m is experimentally demonstrated. [ABSTRACT FROM AUTHOR]