18-10-2016, 02:35 PM
1459678688-FlexibleElectronics.docx (Size: 2.24 MB / Downloads: 4)
I. INTRODUCTION
Ever evolving advances in thin-film materials and devices have fueled many of the developments in the field of flexible electronics. These advances have been complemented with the development of new integration processes, enabling wafer-scale processes to be combined with flexible substrates. This has resulted in a wealth of demonstrators in recent years. Following substantial development and optimization over many decades, thin film materials can now offer a host of advantages such as low cost and large area compatibility, and high scalability in addition to seamless heterogeneous integration.
Diodes and transistors are two of the most common active thin-film devices used in a wide range of digital and analog circuits, as well as for detection and energy generation. While they have been successfully used in flexible platforms, their performance and applicability in systems is limited by a number of factors, in ev it ability requiring use of exotic device architectures, consisting of highly optimized geometries combined with integration of novel materials. This has often facilitated tailoring of the electronic properties toward particular applications that demonstrate vast improvements in form factor, though typically at significant financial cost, which is unacceptable at the en masse scale. Though such one off and the observed scatter is indicative of typical variation in device layout, parasitic capacitance, and supply voltage. Despite this, an overall distinction can be made between different classes of materials.
The field-effect mobility itself is a function of a number of parameters. As well as materials band mobility and the quality of the dielectric/semiconductor interface, it is also influenced by the contact resistance, and the dynamic characteristics of the thin-film transistor (TFT).
Although it is desirable to use thinfilm materials with thehighestpossiblemobility,issuesofcostandscalability play critical roles in material selection. For instance, the two highest mobility materials (Fig. 1) arepolycrystalline silicon(poly-Si)andsemiconductingmetaloxides(MOx). Currently, MOx are costly due to the global localization and shortage of indium. Despite the availability of low-cost Si, the fabrication process of poly-Si is also rather costly, due to postdeposition processing requirements in large-area applications.
Incorporatingnanowires(NWs), carbon nanotubes (CNTs), graphene or other nanomaterialswithinsemiconducting thin films allow tailoring of their properties. Devices based on such composites typically exhibit enhanced electrical performance, such as higher fieldeffect mobility and subthreshold slope, leading to loweroperatingvoltages,