Wet-chemical approaches for surface and interface processing of two-dimensional MX2 semiconductors

While fabrication strategies for Si and SiGe based CMOS technologies are well established, the use of 2D MX2 semiconductors as channel material poses new problems. In such device applications, etching remains an essential step (e.g. layer selective etching, recessing and contamination removal). In contrast to conventional dry etching techniques that can damage the MX2 monolayer, wet-chemical etching provides a simple alternative for obtaining high quality surfaces. The atomic-layer-scale dimensions, however, require ultimate etching selectivity while maintaining the chemical and physical properties of the 2D layer. In order to meet these goals, fundamental understanding is needed on the processes that occur at the MX2/electrolyte interface. These insights will not only enable novel device architectures but will also contribute to the surface and interface passivation research. Insight in surface chemical composition and band energetics will be obtained by both ex-situ and post operando x-ray photoelectron spectroscopy (XPS) and high-resolution synchrotron radiation photoemission spectroscopy (SRPES). These studies on atomic scale etching and passivation will be complemented with ICP-MS measurements, time resolved photoluminescence and electrochemical gating experiments to relate surface chemistry to the optical and electronic properties of 2D MX2 materials. Other physical characterization techniques like elastic recoil detection analysis (ERDA), electrical measurements, atomic force microscopy (AFM), scanning and transmission electron microscopy (SEM, TEM) are available to support my exploratory work.