Experimental technology of single molecule chip preparation

Professor Guo Xuefeng's research group from the School of Chemistry and Molecular Engineering of Peking University has developed a mature single-molecule chip preparation experimental technology, which mainly reveals the two key steps of graphene field-effect transistor preparation and single-molecule anchoring. The single-molecule devices produced by these technologies are universal and will give birth to a new generation of single-molecule electronic devices, which will be cross-integrated with other disciplines and promote the development of new fields of single-molecule cross-science, such as the basic physical properties of single-molecule physics and chemistry, single-molecule chemical reaction kinetics and single-molecule biophysics. The relevant research results, entitled "graphene-molecule-graphene monomolecular junction for detecting electronic reactions on a molecular scale", were published in the international academic journal Nature Protocol a few days ago.
Guo Xuefeng introduced that a single molecule is the basic unit of the material world, the gene that constructs the material world, and the key to regulating the life process. It has rich scientific connotations. Among them, graphene-based single-molecule devices have certain interface coupling, high stability, good tolerance to complex environments, etc., and are expected to create a powerful engine for exploring infinite bottom space.
During the research, the team grew high-quality single-layer graphene on copper sheets by chemical vapor deposition. With the aid of polymethyl methacrylate, after etching the copper sheet, the graphene is transferred to a specific size silicon wafer to meet the requirements of subsequent testing. The graphene is then cut into a strip pattern by oxygen plasma etching. Further, an electrode array is prepared by evaporation to obtain a graphene field effect transistor. Anchoring a single molecule requires the preparation of a series of spaced pairs of graphene electrodes. By electron beam exposure, the dotted window is prepared on the polymethyl methacrylate spin-coated on the surface of graphene, combined with further oxygen plasma isotropic etching and auxiliary electric burning, the graphene point contact can be obtained, and then the electrode pair with carboxyl end and nano-gap can be prepared.
Subsequently, the research team added graphene chips to the flask, and used click chemistry or covalent condensation to prepare covalently anchored monomolecular junctions according to the functional groups at the ends of different molecular bridges. Among them, the anchored single molecule can be further verified by electrical, optical and other multi-modal characterization: including grid voltage-dependent experiments, random optical reconstruction super-resolution imaging, single-molecule spectroscopy and inelastic electron tunneling spectroscopy.
"These technologies use a single molecule to prepare optoelectronic devices, which is a key step for the potential application of molecular electronic devices. It is expected to develop subversive single-molecule chip integration technology and a new generation of precise molecular diagnosis/sequencing technology. It is also expected to provide epoch-making research paradigms and spectroscopy methods for revealing the internal mechanism of material conversion and the intrinsic laws of life phenomena, and then promote the formation of single-molecule cross-science new growth points and scientific and technological breakthroughs." Guo Xuefeng said.

Source: Guangming Daily