In situ Ga-doped ZnO nanotips were grown on amorphous fused silica substrates using metalorganic chemical vapor deposition. Structural, optical, and electrical properties of as-grown ZnO nanotips are investigated. Despite the amorphous nature of fused silica substrates, Ga-doped ZnO nanotips are found to be single crystalline and oriented along the c-axis. Photoluminescence ͑PL͒ spectra of Ga-doped ZnO nanotips are dominated by near-band-edge emission with negligible deep-level emission. The increase in PL intensity from Ga doping has been attributed to the increase of Ga donor-related impurity emission. Current-voltage characteristics of the ZnO nanotips are measured by conductive-tip atomic force microscopy, which shows the conductivity enhancement due to Ga doping.

A one-pot protocol for the synthesis of highly enantiopure benzylic thioethers, thioacetates, and sulfones (94−99% ee) via a ligand-free, copper-catalyzed stereospecific C−S coupling reaction of thiols and enantioenriched tertiary benzylic amines via in situ activation by methyl triflate is developed. Various enantioenriched tertiary benzylic amines, including 1-arylalkylamines, 1-tetrahydronaphthylethylamine, heterocyclic amines (e.g., 1-(thiophen-2-yl)ethanamine), and amino acid esters containing a benzylamine moiety, are highly efficient substrates, and their chirality is efficiently transferred to the products (94−99% ee). The absolute configurations of the products are predictable and follow the pattern of S N 2-type substitutions; an inversion of the absolute configuration of the tertiary amines occurs during the C−S coupling reaction. Not only are various alkene-, arene-, and heteroarenethiols suitable for this C−S coupling reaction but also potassium thioacetate and sodium phenylsulfinate are as well. A plausible mechanism was proposed on the basis of the experimental results.

This new understanding and demonstration of features printed by proximity x-ray lithography allows a revolutionary extension and simplification of otherwise established processes for microfabrication. The ability to produce fine features is controlled predominantly by diffraction and photoelectron blur. The diffraction manifests itself as feature 'bias'. In the classical approach the bias is minimized. Bias optimization in terms of mask/wafer gap and resist processing allows the formation, on a wafer, of features smaller than those on the mask: thus producing local 'demagnification'. This demagnification (×3 − ×6) is achieved without lenses or mirrors, but it offers the same advantages as projection optical lithography in terms of critical dimension control. The photoelectron blur is more or less pronounced depending on exposure dose and development conditions. Resist exposure and process can be optimized to utilize a ∼50% photoelectron energy loss range. In consequence proximity x-ray lithography is extensible to feature sizes below 25 nm, taking advantage of comparatively large mask features (>100 nm) and large gaps (30-15 µm). The method is demonstrated for demagnification values down to ×3.5. To produce DRAM half-pitch fine features, techniques such as multiple exposures with a single development step are proposed.

No abstract

As one of the most significant constituent parts of wearable electronic systems, flexible pressure sensors can accommodate irregular surfaces and perform spatial mapping when subjected to external pressure or strain stimuli. Herein, a wearable flexible pressure sensor integrated with two interlocked micropillar arrays is demonstrated by a facile and cost‐effective metal‐assisted chemical etching (MaCE) method with the assistance of polymer microspheres lithography technique. The flexible sensor, with micropillars of 2.6 µm in diameter, 6.6 µm in height, and 3 µm in pitch, exhibits superior sensitivity of −4.48 kPa−1 (0–100 Pa), rapid response and relaxation time of 52 and 40 ms, respectively, low detection limit of <1 Pa, and outstanding working stability over 5000 cycles of pressure loading/unloading. The prepared sensors are successfully demonstrated in detecting finger motions and monitoring human pulse signals, paving the promising route for its function in wearable electronic skins, soft robotics, and healthcare monitoring devices, etc.