In the past decade, graphene has shown great value in both fundamental sciences and practical applications. In spite of the intense research efforts on achieving chemical‐free, low‐temperature processing of high‐quality graphene, cost‐effective synthetic methods to directly fabricate graphene sheets on a substrate are still lacking. Laser‐induced graphene (LIG) is a recently developed method to directly form graphene from carbon‐rich materials. In this work, combined are theoretical and experimental approaches to systematically investigate the light‐material interactions in LIG fabrication processes. First, developed is a molecular dynamics model to disclose the transient formation process of LIG and identified are the critical parameters that govern this process. Following the theoretical prediction, developed is a system to utilize a picosecond UV laser to directly fabricate graphene from polyimide films at room temperature and under atmospheric pressure. After investigating the effects of the laser processing parameters on the LIG quality and subsequent processing optimization, it is experimentally demonstrated that picosecond UV laser processing can be used to prepare high‐quality LIG. With the newly developed LIG, fabricated is a high‐sensitive proximity sensor.

No abstract

Monolayer nano-sphere arrays attract great research interest as they can be used as templates to fabricate various nano-structures. Plasma etching, and in particular high-frequency plasma etching, is the most commonly used method to obtain non-close-packed monolayer arrays. However, the method is still limited in terms of cost and efficiency. In this study, we demonstrate that a low frequency (40 kHz) plasma etching system can be used to fabricate non-close-packed monolayer arrays of polystyrene (PS) nano-spheres with smooth surfaces and that the etching rate is nearly doubled compared to that of the high-frequency systems. The study reveals that the low-frequency plasma etching process is dominated by a thermal evaporation etching mechanism, which is different from the atom-scale dissociation mechanism that underlines the high-frequency plasma etching. It is found that the polystyrene nano-sphere size can be precisely controlled by either adjusting the etching time or power. Through introducing oxygen as the assisting gas in the low frequency plasma etching system, we achieved a coalesced polystyrene nano-sphere array and used it as a template for metal-assisted chemical etching. We demonstrate that the method can significantly improve the aspect ratio of the silicon nanowires to over 200 due to the improved flexure rigidity.

Directional liquid transport has significant domestic and industrial applications. Tapered objects have theoretically and experimentally been demonstrated to have the ability to spontaneously transport liquids. However, the transporting distance is limited, and consecutively and spontaneously transporting liquids has always been a challenge. In this work we proposed to exploit ladderlike tapered pillars, which are inspired by relay races, to increase the transport distance. These pillars were designed using a developed numerical model and fabricated by a novel alternating etching and coating method followed by wettability enhancement. We demonstrated through experiments that the resulting pillars could consecutively and spontaneously transport a liquid droplet at an average velocity of 0.139 m/s with a maximum acceleration of 5 g. The optimum window of the tilt angle range (0°-25°), contact angle (50°), and the chemical modification time (5 min) were obtained. Such ladderlike tapered pillars are able to improve the water-collection efficiency. These results may provide a new and systematic way to design and fabricate materials and structures for directional liquid transport.

devices, [13] such as fin field-effect transistor effect based metal-oxide-semiconductor field-effect transistor [14,15] and insulated gate bipolar transistors (IGBTs), [16,17] which are used in high-speed railways [18,19] and electric vehicles. [20] Despite these advantages, the unique properties of SiC also raise several challenges for device fabrication. The SiC oxidation reaction isThe ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/smtd.202200329.