Hierarchical Ordering of Quantum Dots and Liquid with Tunable Super‐Periodicity into High Aspect Ratio Moiré Superlattice Structure

Abstract

wileyonlinelibrary.comincluding both bottom-up and top-down approaches, have been developed for the fabrication of complex superlattice structures using the moiré fringe technique. Several bottom-up fabrication methods, which include block-copolymers, [ 4 ] DNA crystals, [ 5 ] polymer microparticles, [ 6 ] colloidal crystals, [ 7 ] and self-assembled nanorod arrays, [ 8,9 ] have been suggested for the formation of moiré superlattice structures. However, such soft-material-based moiré superlattice structures contain many defects and imperfections over a large area, limiting their potential application in areas such as plasmonic substrates, [ 10,11 ] hard templates for lithography, [ 4 ] and self-assembly. [12][13][14] On the contrary, topdown approaches such as nano-imprint lithography, [ 15 ] ion-beam lithography, [ 16 ] mechano-photopatterning, [ 17 ] and rotational-photolithography [ 18 ] produce a highly crystalline superstructure without defects and imperfections, and with high accuracy and reproducibility. Despite considerable progress in this area, major challenges remain in the development of complex nano-scaled moiré patterns with multiple functions and multiple materials, and more research is required to greatly expand their application range. It is essential that the target materials for building up moiré patterns be diverse, from soft to hard materials, forming a robust superstructure. Having a diverse range of materials as candidates for forming moiré patterns can widen their range of application. In addition, complex superlattice structures having diverse functional properties should require only a simple fabrication method with high throughput, without needing complex process conditions or specialized optically sensitive materials.In the study described below, we have developed a new procedure for the construction of multi-functional complex moiré superlattice structures, through an advanced secondary sputtering lithography (SSL) technique. The SSL technique developed by our group can achieve 10 nm scale nano-patterns through the secondary sputtering phenomenon during the ion-bombardment process. [19][20][21][22] A signifi cant step was taken towards the realization of complex nano-scaled moiré superlattice structures, through the use of a multi-step SSL procedure. Along with control over the misorientation angle, we achieved highly periodic and high aspect ratio moiré superlattice In this work, a new approach for construction of high aspect ratio complex moiré superlattice structure with versatile super-periodicity is developed using the moiré fringe and secondary sputtering lithography. Wide assortments of high aspect ratio complex superstructures having different features on a 10 nm scaled wall are easily fabricated from simple starting components. More important is the fi nding of a new microscale phenomenon, consisting in trapping fl uids in the centres of the moiré hexagonal fringes, as the consequence of the modulation of local hydrophilicty of the pattern. Using this phenomenon, target mater...

Recent Progress in Simple and Cost‐Effective Top‐Down Lithography for ≈10 nm Scale Nanopatterns: From Edge Lithography to Secondary Sputtering Lithography

“…A complex moire superlattice structure with high-resolution and high aspect ratio has been developed as a new method based on SSL technology (Figure 8d,e). [165] By using the repetitive SSL process described earlier, very regular moire superlattice structures were successfully fabricated. All the structures Figure 7.…”

High-Resolution p-Type Metal Oxide Semiconductor Nanowire Array as an Ultrasensitive Sensor for Volatile Organic Compounds

“…1c and 1g). [34][35][36][37] In this step, polycrystalline MOS nanowire arrays with a high aspect ratio were formed by the attachment of transition-metal nanoparticles with ~5 nm size. The PS prepattern residue was then removed by oxygen reactive ion etching (RIE) under low-vacuum conditions (Fig.…”

Ten Nanometer Scale WO3/CuO Heterojunction Nanochannel for an Ultrasensitive Chemical Sensor

“…In this study, the concentration ratio was controlled from pure WO 3 (1/0 WO 3 /CuO ratio) to 50/1 and 15/1 by deposition of W and Cu as Cu 0.3 nm/W 29.4 nm/Cu 0.3 nm and Cu 1 nm/W 28 nm/Cu 1 nm, respectively. The deposited bimetal layers were then physically etched and sputtered to the side surface of the prepattern at a wide-angle distribution by an argon ion (Ar + ) bombardment process, which is called the secondary sputtering phenomenon. − In this step, a polycrystalline Cu–W bimetal nanopattern with high aspect ratio was formed by the attachment of metal nanoparticles (∼5 nm size for Cu and ∼10 nm size for W). The selective removal of the PS prepattern was then achieved by oxygen reactive ion etching (RIE) under low-vacuum conditions followed by thermal oxidation of the metal pattern in ambient air in a tubular furnace at 450 °C for 3 h. With thermal oxidation, the metallic nanopatterns of W/Cu were successfully converted to the WO 3 /CuO nanopattern sensing channel.…”