STM Characterization of Wire-Like Growth Modes in MBE-Grown Thin Films

Scanning tunneling microscopy (STM) is a well-established technique used to study and characterize the topographic and electronic properties of material surfaces with atomic resolution. We outline an undergraduate research project using STM to characterize an unexpected wire-like growth mode of heterostructure samples of 2D materials grown by molecular beam epitaxy (MBE). We find that varying growth parameters, such as growth rate, significantly impacts the morphology of the resultant wire-like patterns. Changes in the observed morphology are then characterized using X-ray diffraction (XRD) to determine changes in the structure and phases present in the samples. Finally, we discuss a theoretical model to explain the conditions under which the wires nucleate and grow and the underlying materials physics.