Foil-to-foil lamination and electrical interconnection of printed components on flexible substrates

This paper describes and compares two integration methods to structurally laminate and interconnect foil-based components with flexible polymeric substrates. The first method uses isotropic conductive adhesives (ICA) confined in laser-ablated through foil vias (TFV), while the second one uses an anisotropic conductive adhesive (ACA). Both procedures were successfully demonstrated by interconnecting silver-based inkjet printed and gold-sputtered interdigitated capacitive humidity sensors onto flexible PEN carrier substrates, showing functionality, high process yield and low-complexity. The robustness of the assemblies was tested and compared for adhesion, bending, high humidity and temperature cycling. Confined ICA vias show higher mechanical robustness to bending, while both methods remained functional after more than 900 h of environmental ageing. Finally, the interconnections were fully validated at different levels of relative humidity (RH) by comparing the sensor response to that of a commercial sensor. © 2013 Elsevier B.V. All rights reserved

Asymmetric Split-Gate Ambipolar Transistor and Its Circuit Application to Complementary Inverter

114Nsciescopu

Monolayer coverage and channel length set the mobility in self-assembled monolayer field-effect transistors

The mobility of self-assembled monolayer field-effect transistors (SAMFETs) traditionally decreases dramatically with increasing channel length. Recently, however, SAMFETs using liquid-crystalline molecules have been shown to have bulk-like mobilities that are virtually independent of channel length. Here, we reconcile these scaling relations by showing that the mobility in liquid crystalline SAMFETs depends exponentially on the channel length only when the monolayer is incomplete. We explain this dependence both numerically and analytically, and show that charge transport is not affected by carrier injection, grain boundaries or conducting island size. At partial coverage, that is when the monolayer is incomplete, liquid-crystalline SAMFETs thus form a unique model system to study size-dependent conductance originating from charge percolation in two dimensions.

Tunable doping of a metal with molecular spins

The mutual interaction of localized magnetic moments and their interplay with itinerant conduction electrons in a solid are central to many phenomena in condensed-matter physics, including magnetic ordering and related many-body phenomena such as the Kondo effect(1), the Ruderman-Kittel-Kasuya-Yoshida interaction(2) and carrier-induced ferromagnetism in diluted magnetic semiconductors(3). The strength and relative importance of these spin phenomena are determined by the magnitude and sign of the exchange interaction between the localized magnetic moments and also by the mean distance between them. Detailed studies of such systems require the ability to tune the mean distance between the localized magnetic moments, which is equivalent to being able to control the concentration of magnetic impurities in the host material. Here, we present a method for doping a gold film with localized magnetic moments that involves depositing a monolayer of a metal terpyridine complex onto the film. The metal ions in the complexes can be cobalt or zinc, and the concentration of magnetic impurities in the gold film can be controlled by varying the relative amounts of cobalt complexes (which carry a spin) and zinc complexes (which have zero spin). Kondo and weak localization measurements demonstrate that the magnetic impurity concentration can be systematically varied up to similar to 800 ppm without any sign of inter-impurity interaction. Moreover, we find no evidence for the unwanted clustering that is often produced when using alternative methods