We demonstrate the ability to precisely control the alignment and placement of large numbers of InAs nanowires from solution onto very narrow, prepatterned electrodes using dielectrophoresis. An understanding of dielectrophoretic behavior associated with such electrode geometries is essential to development of approaches for assembly of intricate nanowire systems. The influence of signal frequency and electrode design on nanowire manipulation and placement is examined. Signal frequencies in the range of 10 MHz are found to yield high percentages of aligned nanowires on electrodes with dimensions similar to that of the nanowire. Strategies for further improvement of nanowire alignment are suggested and analyzed.

Articles you may be interested inFerromagnet-semiconductor nanowire coaxial heterostructures grown by molecular-beam epitaxy Appl. Phys. Lett. 95, 133126 (2009); 10.1063/1.3240405 Strain distribution and interface modulation of highly lattice-mismatched InN/GaN heterostructure nanowires Appl. Phys. Lett. 95, 033112 (2009);We present a methodology to determine critical dimensions for coherently strained coaxial nanowire heterostructures based on a well-known formalism used to determine the critical thickness in planar epitaxial growth. The unique geometry of the nanowire structure along with the volumetric similarity of the core and shell regions give rise to a number of possible stable core-shell configurations for a given choice of materials. We show that a unique critical core radius and critical shell thickness, dependent on core radius, can quantify these configurations. Illustrative calculations are presented for various nitride semiconductor-based core-shell structures. It is anticipated that this model will serve as a guide to determine the feasibility of specific coherently strained nanowire heterostructure designs.

We employ a methodology, based on established approaches for determining the critical thickness for strain relaxation in planar films, to determine critical dimensions for coherently strained coaxial nanowire heterostructures. The model is developed and executed for various specific core-shell heterostructures in ͓111͔ zinc blende and ͓0001͔ wurtzite geometries. These calculations reveal that critical dimensions in such heterostructures can be quantified by a unique critical core radius and a critical shell thickness, which is dependent on the core radius. It is anticipated that this work will serve as a guide to determine the feasibility of specific coherently strained nanowire heterostructure designs.

Silicon nanowire (SiNW) field-effect transistors (FETs) were fabricated from nanowire mats mechanically transferred from a donor growth wafer. Top- and bottom-gate FET structures were fabricated using a doped a-Si:H thin film as the source/drain (s/d) contact. With a graded doping profile for the a-Si:H s/d contacts, the off-current for the hybrid nanowire/thin-film devices was found to decrease by 3 orders of magnitude. Devices with the graded contacts had on/off ratios of ∼10(5), field-effect mobility of ∼50 cm(2)/(V s), and subthreshold swing of 2.5 V/decade. A 2 in. diagonal 160 × 180 pixel image sensor array was fabricated by integrating the SiNW backplane with an a-Si:H p-i-n photodiode.

Articles you may be interested inQuantitative potential measurements of nanoparticles with different surface charges in liquid by open-loop electric potential microscopy Electric field induced reversible tuning of resistance of thin gold films Laser induced gratings enhanced by surface-charge mediated electric field in doped nematic liquid crystals