Understanding the effect of defects on the performance of 2D materials
Two-dimensional (2D) semiconductors have the potential to complement silicon as a channel material in advanced CMOS devices. As opposed to silicon, these materials are monolayer-thin and markedly less sensitive to detrimental effects encountered in channels with strongly reduced physical dimensions. At this point in time, however, experimental device results are not yet on par with their theoretical performance, which is amongst others due to insufficient material quality. Intrinsic and extrinsic defects strongly influence the electronic properties of 2D materials. However, to date, a systematic methodology to determine their role in the electronic performance of 2D layers is lacking. By combining different defect characterization methods (e.g. optical and electrical measurements, scanning probe techniques, etc.), this Ph.D. project will attempt to answer such challenging questions as: What lies at the origin of interface defects? Are they coming from the oxide selection (e.g. SiO2, HfO2, SiN, hBN) or from the interface properties (e.g. roughness, moisture, carbon)? How important are intrinsic defects in the MX2 layers, and what is their electrical impact?