Multiple Conduction Paths Research Articles

Silicon Nanoparticles in Graphene Sponge for Long-Cycling-Life and High-Capacity Anode of Lithium Ion Battery

A microwave plasma enhanced chemical vapor deposition (MPECVD) method is used to synthesize nanocarbon structures on silicon particles. The structure is analyzed by scanning electron microscope (SEM), Raman spectroscopy and X-ray diffractometer (XRD). The results show that silicon particles are surrounded by wall-like nanographite and multilayer graphene, also known as graphene nanowalls (GNWs). The nanocarbon structures provide excellent chemical and electrochemical properties and good electrical conductivity enabling much improved performance of lithium ion batteries (LIBs) anode made of nanocarbon coated silicon particles. LIBs maintain the high capacity of 2000 mAh/g for 100 cycles of charging and discharging exhibiting very little decrease in capacity. Graphene nanowalls provide multiple conductive paths for silicon particles to remain being electrically connected to the external circuits allowing lithium ions and electrons to enter and leave silicon particles for charging and discharging.

Carrier Localization Suppression by Multipath Transport in Helical Polyacetylene

The conduction sites in the main chain of helical polyacetylene (HPA) are arranged in a unique helical configuration, whereas conventional conductive polymers such as cis-polyacetylene and trans-polyacetylene have almost collinearly aligned conduction sites. Here we report the distinctive hole transport properties in HPA caused by the helical structure. Analyses of the hole diffusion with different models of the range of transfer integrals (TIs) reveal that the helical configuration produces multiple conduction paths in HPA. The holes propagate through multiple pathways, avoiding local paths with small TIs. This mechanism suppresses the localization of electronic states in HPA, which is inevitable in conventional one-dimensional conductive polymers.

Erratum to: Transdermal power transfer for recharging implanted drug delivery devices via the refill port

The most important aspects of the design are power handling capability, isolation of the drug and tissue from electrical current, minimal tissue and drug heating, and ease of alignment between the needle and the port. In order to transfer DC power, the needle should be composed of at least two conductors, or poles, which must mate with corresponding poles in the refill port. The conductive path should also be electrically isolated. (The isolation is particularly important if the needle is being used to refill the drug reservoir at the same time the battery is being recharged. While this capability is not fundamentally required, it can improve efficiency and convenience.) Structural options for providing multiple conductive paths in a single needle include the use of multiple conductors within the lumen, the use of concentric isolated conductors, or splitting the needle longitudinally and isolating the halves. The split needle allows for simple alignment because it provides access to both conductors on the exterior of the needle. Sub-section 2.1 outlines the power transfer design constraints of the needle; sub-section 2.2 outlines the design of the mating mechanism and the port for use with the multi-pole needle; sub-section 2.3 describes the assembly procedure for the needle and the refill port.

Multiple conduction paths in boron δ-doped diamond structures

Impedance spectroscopy has been used to investigate conductivity within boron-doped diamond in an intrinsic/delta-doped/intrinsic (i-δ-i) multilayer structure. For a 5 nm thick delta layer, three conduction pathways are observed, which can be assigned to transport within the delta layer and to two differing conduction paths in the i-layers adjoining the delta layer. For transport in the i-layers, thermal trapping/detrapping processes can be observed, and only at the highest temperature investigated (673 K) can transport due to a single conduction process be seen. Impedance spectroscopy is an ideal nondestructive tool for investigating the electrical characteristics of complex diamond structures.

Magnetoresistance effect in spin-polarized junctions of ferromagnetically contacting multiple conductive paths: Applications to atomic wires and carbon nanotubes

For spin-polarized junctions of ferromagnetically contacting multiple conductive paths, such as ferromagnet (FM)/atomic wires/FM and FM/carbon nanotubes/FM junctions, we theoretically investigate spin-dependent transport to elucidate the intrinsic relation between the number of paths and conduction, and to enhance the magnetoresistance (MR) ratio. When many paths are randomly located between the two FMs, electronic wave interference between the FMs appears, and then the MR ratio increases with increasing number of paths. Furthermore, at each number of paths, the MR ratio for carbon nanotubes becomes larger than that for atomic wires, reflecting the characteristic shape of points in contact with the FM.

Influence of nonuniform charge distribution in In 0.53Ga 0.47As on the interpretation of dopant incorporation

The electrical properties of In 0.53Ga 0.47As grown on full two-inch InP wafers have been studied. Special emphasis was placed on investigations of the vertical and lateral uniformity of the material quality. Using the Mobility Spectrum Technique, a way of unambiguously analyzing Hall effect data from samples with multiple conduction paths, a conducting substrate-epi interface layer was found in some In 0.53G 0.47As films. Despite the presence of the interface layer, good, vertically uniform mobilities in n-doped samples were still measured in the film. A large-scale lateral nonuniformity in the sheet resistance was associated with variations in the interface layer. A 1.5 μm thick undoped In 0.52Ga 0.47As layer with an In 0.52Al 0.48As buffer layer exhibited a 77K mobility of 65,100 cm 2/V⋯s with no sign of interface conduction. Some lateral nonuniformity in the sheet resistance similar to the doped sample was still observed, indicating that the substrate surface quality still affects the film quality to some degree. However, the lateral variations in films with AlInAs buffers are much smaller and are not expected to affect, e.g., modulation-doped structures.