A combinatorial approach of developing alloy thin films using co-sputtering technique for displays

In this study we have used a combinatorial approach for producing binary and ternary alloy thin film libraries using a lab-scale RF co-sputtering system.Initially we used two elemental sputtering targets,i.e.aluminum(Al) target and neodymium(Nd) target,to produce a film library of varying composition and successfully identified a suitable composition range(1.95-2.38 at%Nd) in which resistance to hillock formation and resistivity of the film spots were found to be satisfactory in annealed state(350°C,30 min) .In another case,in order to form ternary alloy composition library we have used two sputtering targets,i.e.an Al-0.5 at%Nd alloy target and an elemental Ni target.Though,co-sputtered Al-0.6 at% Nd-0.9 at%Ni alloy films showed satisfactory resistance to hillock formation and low resistivity after annealing,film deposited from a ternary alloy target with the same composition failed to show satisfactory resistance to hillock formation during annealing.In case of Al-0.6 at%Nd-0.9 at%Ni alloy target,250 nm thick film showed poor resistance to hillock formation than the 500 nm thick film.This clearly showed thickness-dependent hillock performance of Al-0.6 at%Nd-0.9 at%Ni alloy.In this study it was found that,in addition to the process variables,metallurgical microstructure of the alloy sputtering targets had significant effect on the film properties which was not obvious from the results of films deposited using co-sputtering of the individual elemental targets.     

Medium-scale carbon nanotube thin-film integrated circuits on flexible plastic substrates

The ability to form integrated circuits on flexible sheets of plastic enables attributes (for example conformal and flexible formats and lightweight and shock resistant construction) in electronic devices that are difficult or impossible to achieve with technologies that use semiconductor wafers or glass plates as substrates. Organic small-molecule and polymer-based materials represent the most widely explored types of semiconductors for such flexible circuitry. Although these materials and those that use films or nanostructures of inorganics have promise for certain applications, existing demonstrations of them in circuits on plastic indicate modest performance characteristics that might restrict the application possibilities. Here we report implementations of a comparatively high-performance carbon-based semiconductor consisting of sub-monolayer, random networks of single-walled carbon nanotubes to yield small- to medium-scale integrated digital circuits, composed of up to nearly 100 transistors on plastic substrates. Transistors in these integrated circuits have excellent properties: mobilities as high as 80 cm(2) V(-1) s(-1), subthreshold slopes as low as 140 m V dec(-1), operating voltages less than 5 V together with deterministic control over the threshold voltages, on/off ratios as high as 10(5), switching speeds in the kilohertz range even for coarse (approximately 100-microm) device geometries, and good mechanical flexibility-all with levels of uniformity and reproducibility that enable high-yield fabrication of integrated circuits. Theoretical calculations, in contexts ranging from heterogeneous percolative transport through the networks to compact models for the transistors to circuit level simulations, provide quantitative and predictive understanding of these systems. Taken together, these results suggest that sub-monolayer films of single-walled carbon nanotubes are attractive materials for flexible integrated circuits, with many potential areas of application in consumer and other areas of electronics.