Recent advances in lithographic fabrication of micro-/nanostructured polydimethylsiloxanes and their soft electronic applications

The intensive development of micro-/nanotechnologies offers a new route to construct sophisticated architectures of emerging soft electronics.Among the many classes of stretchable materials,micro-/nanostructured poly(dimethylsiloxane)(PDMS)has emerged as a vital building block based on its merits of flexibility,stretchability,simple processing,and,more importantly,high degrees of freedom of incorporation with other functional materials,including metals and semiconductors.The artificially designed geometries play important roles in achieving the desired mechanical and electrical performances of devices and thus show great potential for applications in the fields of stretchable displays,sensors and actuators as well as in health-monitoring device platforms.Meanwhile,novel lithographic methods to produce stretchable platforms with superb reliability have recently attracted research interest.The aim of this review is to comprehensively summarize the progress regarding micro-/nanostructured PDMS and their promising soft electronic applications.This review is concluded with a brief outlook and further research directions.

Fabrication of Anti-reflecting Si Nano-structures with Low Aspect Ratio by Nano-sphere Lithography Technique

Nano-structured photon management is currently an interesting topic since it can enhance the optical absorption and reduce the surface reflection which will improve the performance of many kinds of optoelectronic devices, such as Si-based solar cells and light emitting diodes. Here, we report the fabrication of periodically nano-patterned Si structures by using polystyrene nano-sphere lithography technique. By changing the diameter of nano-spheres and the dry etching parameters, such as etching time and etching power, the morphologies of formed Si nano-structures can be well controlled as revealed by atomic force microscopy.A good broadband antireflection property has been achieved for the formed periodically nano-patterned Si structures though they have the low aspect ratio(<0.53). The reflection can be significantly reduced compared with that of flat Si substrate in a wavelength range from 400 nm to 1200 nm. The weighted mean reflection under the AM1.5 solar spectrum irradiation can be as low as 3.92% and the corresponding optical absorption is significantly improved, which indicates that the present Si periodic nano-structures can be used in Si-based thin film solar cells.

The Examination of the Tangut Garland Sutra(Avatamsaka Sūtra) Volume 41 in the C.V.Starr East Asian Library at University of California,Berkeley

This paper introduces the unpublished copy of a Tangut script Garland Sutra华严经(or Flower Ornament Sutra) volume/juan 41第四十一卷stored at the C.V.Starr East Asian Library at the University of California,Berkeley.It reinforces the assessment of this manuscript as a modern forgery.Through comparing various physical features of the same volume stored in other countries,and the history of their acquisition,this paper traces the lithographic reproduction of this volume to the early twentieth century and its later circulation.This research also compares the Berkeley copy with the Princeton copy of volume 77 which is the other only known Tangut Garland Sutra in America.The fundamental difference between the two copies prove that the former was a modern forgery but the latter a Yuan period product of movable type wooden block print.

Lithographic patterning of ferromagnetic FePt nanoparticles from a single-source bimetallic precursor containing hemiphasmidic structure for magnetic data recording media

Patterning of L10 FePt nanoparticles(NPs) with high coercivity offers a promising route to develop bit-patterned media(BPM) for the next generation magnetic data recording system, but the synthesis of monodisperse FePt NPs and mass production of their nanopatterns has been a longstanding challenge. Here, highly efficient nanoimprint lithography was applied for large-scale universal patterning, which was achieved by imprinting the solution of a single-source bimetallic precursor. The rigid coplanar metallic cores and the surrounding flexible tails in the bimetallic complex permit the spontaneous molecular arrangements to form the highly ordered negative morphology replicated from the soft template.In-situ pyrolysis study was then investigated by one-pot pyrolysis of the precursor under an Ar/H2 atmosphere, and the resultant NPs were fully characterized to identify the phase,morphology and magnetic properties. Finally, highly-ordered patterns on certain substrates were preserved perfectly after pyrolysis and could be potentially utilized in magnetic data recording media.

Effect of Free Radicals on Irradiation Chemistry of a Double-Coordination Organotin(Sn_(4))Photoresist by Adjusting Alkyl Ligands

Metal oxide cluster(MOC)photoresists are highly promising materials for the next generation of extreme ultraviolet lithography(EUVL).The consecutive exploration of novel MOC materials and their structural irradiation chemistry are the major concerns associated with EUVL.Herein,we report two bicoordinated tin-oxo clusters(TOCs),the organic ligands of which contain both adamantane carboxylic acids and alkyl groups(methyl:Sn_(4)–Me–C10;butyl:Sn_(4)–Bu–C10).We explore the correlation between the structures of the TOCs and their patterning properties by adjusting the alkyl groups coordinated to the Sn atom.The structural variation causes different irradiation chemistry,with Sn_(4)–Me–C10 exhibiting improved resolution and Sn_(4)–Bu–C10 demonstrating higher sensitivity.These differences are attributed to the bonding energies of the Sn-methyl and Sn-butyl groups,the size of the resulting alkyl radicals,and their reaction probabilities.Both clusters occur in the reactions of Sn–C bond cleavage and the decarboxylation of adamantane carboxylic acids upon irradiation.However,the entire process exhibits distinct characteristics.Based on the electron-beam lithography and other experiments,we proposed irradiationinduced reaction mechanisms for both clusters.The Sn_(4)–Bu–C10 cluster predominantly undergoes alkane chain linkage,whereas the Sn_(4)–Me–C10 cluster mainly follows the adamantanes linkage pathway.