Bottom-up nanoscale patterning and selective deposition on silicon nanowires

We demonstrate a bottom-up process for programming the deposition of coaxial thin films aligned to the underlying dopant profile of semiconductor nanowires. Our process synergistically combines three distinct methods – vapor-liquid-solid (VLS) nanowire growth, selective coaxial lithography via etching of surfaces (SCALES), and area-selective atomic layer deposition (AS-ALD) – into a cohesive whole. Here, we study ZrO2 on Si nanowires as a model system. Si nanowires are first grown with an axially modulated n-Si/i-Si dopant profile. SCALES then yields coaxial poly(methyl methacrylate) (PMMA) masks on the n-Si regions. Subsequent AS-ALD of ZrO2 occurs on the exposed i-Si regions and not on those masked by PMMA. We show the spatial relationship between nanowire dopant profile, PMMA masks, and ZrO2 films, confirming the programmability of the process. The nanoscale resolution of our process coupled with the plethora of available AS-ALD chemistries promises a range of future opportunities to generate structurally complex nanoscale materials and electronic devices using entirely bottom-up methods.

Supramolecular Chemistry: Host–Guest Molecular Complexes

In recent times, researchers have emphasized practical approaches for capturing coordinated and selective guest entrap. The physisorbed nanoporous supramolecular complexes have been widely used to restrain various guest species on compact supporting surfaces. The host–guest (HG) interactions in two-dimensional (2D) permeable porous linkages are growing expeditiously due to their future applications in biocatalysis, separation technology, or nanoscale patterning. The different crystal-like nanoporous network has been acquired to enclose and trap guest molecules of various dimensions and contours. The host centers have been lumped together via noncovalent interactions (such as hydrogen bonds, van der Waals (vdW) interactions, or coordinate bonds). In this review article, we enlighten and elucidate recent progress in HG chemistry, explored via scanning tunneling microscopy (STM). We summarize the synthesis, design, and characterization of typical HG structural design examined on various substrates, under ambient surroundings at the liquid-solid (LS) interface, or during ultrahigh vacuum (UHV). We emphasize isoreticular complexes, vibrant HG coordination, or hosts functional cavities responsive to the applied stimulus. Finally, we critically discuss the significant challenges in advancing this developing electrochemical field.

Fabricating Elastomeric Photomask with Nanosized-Metal Patterns for Near-Field Contact Printing

When an elastomeric photomask is used for near-field contact printing, the high deformability of the elastomer mask plate enables gap-free full contact with the substrate, minimizing the effect of diffraction. This image-transfer technique provides sub-50 nm resolution and depth-of-focus-free lithographic capability with cost-efficient equipment. However, the method’s application is limited due to the lack of a wellestablished protocol for fabricating a nanoscale mask pattern on an elastomeric substrate, which remains a major technical challenge in the field of near-field contact printing. In this study, we present a reliable protocol for fabricating a metal-embedded polydimethylsiloxane (PDMS) photomask. Our fabrication protocol uses conventional nanofabrication processes to fabricate nanosized chromium mask patterns and then transfers the chromium patterns to an elastomeric mask plate using a sacrificial Ni layer. Our protocol provides a high flexibility mask pattern design, and highly stable metal patterns during transferring process. By careful optimizing the experimental parameters, we determined a perfect pattern transfer ratio, which avoided any mechanical failure of the metal pattern, such as debonding or wrinkling. We then fabricated a PDMS photomask and confirmed its nanoscale patterning resolution, with the smallest feature 51 nm in width under a 400-nm light source. We anticipate that our fabrication protocol will enable the application of cost-efficient and high-resolution near-field photolithography.

Extending nanoscale patterning with multipolar surface plasmon resonances

Plasmonic excitation of metallic nanoparticles can trigger chemical reactions at the nanoscale. Such optical effects can also be employed to selectively and locally graft photopolymer layers at the nanostructure surface,...

Correction: Extending nanoscale patterning with multipolar surface plasmon resonances

Correction for ‘Extending nanoscale patterning with multipolar surface plasmon resonances’ by Issam Kherbouche et al., Nanoscale, 2021, 13, 11051–11057, DOI: 10.1039/D1NR02181H.