Scanning Probe Microscopy of Two-dimensional (2D) Field Effect Transistors

Transition Metal Dichalcogenides (TMDs) are 2D van der Waals materials of interest as many of them are semiconducting, opening opportunities for developing ultra-thin components such as field effect transistors. Scanning Tunneling Microscopy (STM) and Atomic Force Microscopy (AFM) are invaluable tools for the development of such devices as they map morphology and electronic properties down to the atomic level. This enables concomitant characterization of a material’s electronic band structure, surface morphology and defects, all contributing to the behavior of the macroscopic devices. Development of TMD devices involves layer-by-layer assembly, followed by surface cleaning methods such as thermal annealing, aimed to remove residual polymers from fabrication. However, this can alter the properties of an electronic device, for example by introducing defects or electrostatic potentials. In this presentation, we aim to characterize topographic features of WSe₂ devices fabricated on Si/SiO₂ using a room temperature, ambient atmosphere STM/AFM and we seek to identify changes in the defect density upon heating at different temperatures. These results give insights into the microscopic behavior of electrons in 2D materials, helping to optimize the performance of 2D electronic devices.