This review surveys recent developments of DNA nanotechnology related to its applications in nanoelectronics industry. The authors start with a brief introduction of DNA nanostructures, followed by a focused discussion of various DNA-based fabrication approaches that are relevant to the semiconductor industry, including DNA-based doping of semiconductor materials, DNA-based fabrication of nanostructures of metallic, dielectric, and semiconductor materials, and DNA-based lithographic patterning of Si, SiO 2 , metal, graphene, and polymer substrates. Examples of DNA-templated fabrication of prototype nanoscale transistors and sensors are highlighted. Finally, major technical challenges facing the future applications of DNA nanotechnology in nanoelectronics and beyond are discussed.

Metrics & MoreArticle Recommendations CONSPECTUS:The surface of 2D materials can spontaneously adsorb and react with molecules in the environment during their processing and storage. This effect, while having a significant impact on many properties of 2D materials, is not always recognized and accounted for in the research involving them. This Account summarizes our recent work in understanding how the ambient environment impacts the properties of 2D materials and its mitigation strategies. We highlight graphene and hydrocarbons in our discussion and complement it with selected studies involving other 2D materials as well as water and oxygen.When graphene and graphite are exposed to air and water, their surfaces adsorb the residue hydrocarbons, typically at part-pertrillion to part-per-billion levels, in the environment. The adsorption of hydrocarbons reduces the surface energy of graphene and graphite and creates a barrier between them and the electrolyte. As a result, the wettability and electrochemical properties of graphene and graphite can be significantly altered by mere exposure to the ambient environment. These changes can be very significant yet highly variable depending on the local environment: several hours of air exposure can increase the water contact angle of graphene by up to 40°and reduce the double-layer capacitance of graphite by up to 50%! The high hydrophobicity and poor electrochemical performance of pristine graphitic carbons, once believed to be intrinsic properties of these materials, are largely due to unintentional surface contamination. The same type of hydrocarbon adsorption was reported for many other 2D materials, such as MoS 2 , hexagonal BN, and mica. In the case of mica, which is highly ionic in nature, the adsorption of hydrocarbons disrupts its interaction with ionic liquid and alters the self-assembly structure of ionic liquid at the mica surface. Similarly, water also impacts the surface properties of graphene in several ways. Water vapor can compete with hydrocarbons for adsorption onto the surface of graphene, thus reducing the rate of hydrocarbon contamination. Water can intercalate between graphene and some of its supporting substrate, altering their interactions. Finally, water enhances the doping of 2D materials by O 2 by promoting an electrochemical doping mechanism involving the O 2 /H 2 O redox couple.Reducing and reversing the surface contamination of 2D materials can greatly enhance material and device performances. While completely stopping the contamination is still challenging, a high-humidity environment is shown to reduce the rate of contamination, as mentioned above. For samples already contaminated by airborne hydrocarbons, their surface properties can be partially restored by treatment in high-vacuum, high-temperature, or mildly oxidative environments.

This paper reports the effect of mechanically applied elastic strain on the hydrogen evolution reaction (HER) activity of graphene under acidic conditions. An applied tensile strain of 0.2% on a graphene electrode is shown to lead to a 1−3% increase in the HER current. The tensile strain increases HER activity, whereas compressive strain decreases it. Density functional theory (DFT) calculations using a periodic graphene slab model predict an increase in the adsorption energy of the H atom with growing tensile strain, consistent with an enhancement of the current density in HER, similar to that observed experimentally.

It is commonly accepted that during conductive atomic force microscopy (CAFM) measurement in ambient, a liquid meniscus can form between the tip and the sample. Such a liquid bridge, normally assumed to be composed of water, is a major factor in analyzing and understanding CAFM results. Here, we show that the adsorption of adventitious hydrocarbons from the air to a surface can greatly affect CAFM data both in imaging mode and in local spectroscopy (current–voltage or I – V curves). We propose a model to explain the phenomena whereby hydrocarbon contaminates contribute to the composition of the liquid bridge between the tip and the sample.

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