EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Understanding the mechanisms governing large scale defect and contaminants in CVD grown 2D materials on transition metal catalysts and their transfer to target substrates are of crucial importance when creating high performance devices. Contamination introduced during transfer and handling is one of the most common factors why devices underperform. The interface between 2D layers in a heterostructure is of great importance when comes to the device performance. A clear understanding of which contaminants affect the most the electrical characteristics of such devices is still overlooked. This research is focusing on understanding the types of contaminations introduced during transfer and fabrication of 2D heterostructures and how these relate to their electrical properties. Here, Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) has been used to monitor the interface composition of hBN/graphene/hBN, hBN/WS2/hBN and graphene/WS2 heterostructures. Comparison was done between exfoliated samples and CVD grown samples. Due to the gentle argon cluster sputtering we were able to obtain sub-monolayer sputtering resolution with reduced roughness. Lastly, we discuss ways to address these contaminants found at the interface.