Microscopic Electronic and Mechanical Properties of Ultra-Thin Layered Materials
Technical Report,01 Apr 2011,31 Mar 2016
COLUMBIA UNIV NEW YORK NEW YORK United States
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The research goals of this project were to characterize the microscopic electronic and structural properties of ultra-thin few layer crystalline materials, commonly referred to as 2D materials. The technical approach used was to perform atomic-resolution scanning tunneling microscopy along with nanofabrication and transport measurements. The materials studied under the grant were graphene and transition metal dichalcogenides. In graphene, studies centered on material created by the chemical vapor deposition technique. A number of studies were conducted to determine the optimal conditions to grow graphene under. The doping of graphene with foreign atoms was investigated extensively. Finally, exotic electronic states in graphene that can be induced via substrate and adatom interactions were investigated. In the transition-metal dichalcogenides, studies initially focused on the charge density wave materials. It was discovered that the charge density wave transition is extremely sensitive to disorder. It was then found that the charge density wave is not driven by Fermi surface nesting, but rather by strong electron-phonon coupling. Superconductivity in transition metal dichalcogenides was then investigated, and it was found that in the limit of thin samples. a new Bose metal state emerges in the presence of a magnetic field. Finally, semiconducting transition metal dichalcogenides grown by metal organic chemical vapor deposition were studied and their atomic and electronic quality were measured by scanning tunneling microscopy.
- Solid State Physics