Intrinsic electrical characterization of two-dimensional transition metal dichalcogenides via scanning probe microscopy

See all webinars in the “Image your way to nature” series here. In a conventional planar silicon field effect transistor (FET), the gate controllability becomes weaker when its lateral dimension becomes smaller than the transistor thickness, which results in adverse short-channel effects, including leakage current, saturation of the carrier mobility in the channel, channel hot-carrier degradation, and time-dependent dielectric breakdown. Hence, the transistor body thickness needs to be reduced to ensure efficient electrostatic control from the gate. Due to the atomic thickness and dangling bond-free surface of two-dimensional (2D) materials, theoretical studies have shown that particularly 2D transition metal dichalcogenides (TMDs), can outperform Si as the channel material, enable the atomic-level scaling, excellent electrostatic gate control, decrease off-state power consumption and further extend Moore’s Law. Suitable techniques to characterize the intrinsic physical and electrical properties of as-deposited 2D materials, are a key link between the quality of as-deposited 2D materials and the performance of 2D materials based electronic devices. This link can help us to better understand, control and improve the performance of 2D materials-based devices. However, techniques for analyzing the intrinsic electrical properties of as-deposited 2D materials on the nanoscale without any transfer and patterning process are limited. In this seminar, scanning probe microscopy (SPM) is used to investigate the intrinsic electrical properties of as-deposited 2D TMDs. Conductive atomic force microscope (CAFM) is performed directly on the surface of as-grown 2D materials without any patterning. CAFM allows correlating the electrical conductivity of as-grown 2D materials to their topography, thereby linking the electrical properties of 2D materials to their physical properties such as layer thickness and chemical bonds, etc. With all of this, CAFM gives us comprehensive information of as-deposited 2D materials and helps us to evaluate the impact of these intrinsic properties on 2D materials based nanoelectronics.