Molecular and NanoPhysics

Responsibles: Klaus Leifer, Hu Li, YuanYuan Han

Graphene, a single layer of carbon with hexagonal lattice, is a fantastic material due to its extraordinary properties, such as highest strength, highest electron mobility, ultra-strong adhesion, etc. In ELMIN group, we are interested in the defect engineering on graphene structure as well as enhancement of various properties and functionalization. Current projects are mainly:

• Improved gas sensing property of graphene gas sensor based on defect engineering of graphene structure
• Graphene Hall effect measurement
• Quantitative mechanical mapping of defective graphene by using Peakforce QNM
• Synthesis of graphene nanoscrolls and following property characterization
• Local fluorination of graphene induced by focused ion beam irradiation
• Graphene hydrogenation and silylation by utilizing photochemistry methods
• Graphene surface functionalization by polymer chemistry and TEM structure imaging

Responsibles: Klaus Leifer, Hassan Jafri, Ishtiaq Hassan Wani

One of the alternate ways to reduce the feature size of electronic components is to use molecules as basic building units. We at ELMiN develop methodologies to (i) characterize electrical as well as mechanical properties of organic molecules and organometallic complexes and (ii) build devices that perform functionalities similar to solid state counterparts e.g. sensors, but use molecules as functional unit. We have developed nanoelectrodes-nanoparticle-molecule bridge platform which can be used for contacting different molecules electrically. Then the platform can be used to electrically probe the molecular vibrational signatures and detect intermolecular interactions (sensor). The nanoelectrodes are also used for characterizing homogeneous and heterogeneous semiconductor nanowires.

Responsibles: Klaus Leifer, Anumol Ashokkumar

Ultrathin semiconductor hetero-nanowires/nanorods synthesized by wet chemical methods are investigated for their electrical and opto-electrical characteristics. Langmuir-Blodgett technique and dielectrophotoc trapping are employed for the assembly of the nanowires onto nanoelectrode devices to facilitate its characterization and further applications. For example, ultrathin superlattice nanowires of ZnS-CdS are developed into monolayer thin films on SiO2/Si substrates and nanoelectrode devices using Langmuir-Blodgett technique and CdSe-CdS nanorods are assembled between the nanoelectrodes by means of dielectrophoretic trapping. Microscopy techniques including Scanning Electron Microscopy, Transmission Electron Microscopy and Atomic Force Microscopy serve as ideal tools for the characterization of such nanostructures and their assembly. The electrical characterization of such sub 2 nm wires /rods is achieved through a nano-platform where the electrodes with a spacing of ~ 30 nm are fabricated using lithography and Focused Ion Beam technique. The research project attempts to bridge the gap between wet chemical synthesis of ultrathin semiconductor nanowires and their device fabrication.