Sample preparation techniques for MoS2: Insights from Auger electron spectroscopy

Abstract

The quest for a pristine MoS2 foil surface involves navigating potential contamination introduced during sample preparation. Evidence suggests that some procedures used to obtain a clean surface may inadvertently introduce contaminants or enhance the adsorption of environmental components prior to analysis. Established cleavage or exfoliation methods, proposed over decades, offer reliability for being less harmful to structure and composition; however, concerns persist regarding subsequent contamination. Sputtering with ionized noble gases is an efficient approach to remove surface impurities under vacuum conditions, though it requires careful attention to potential structural damage from energetic ions. In this study, Auger electron spectroscopy (AES) was employed to assess chemical composition before and after preparation, providing insights into surface alterations. Various experimental conditions were explored to reveal differences in chemical composition from surface to deeper regions during the cleaning process. A comparative analysis of surface sputtering with He+, Ne+, and Ar+ beams at 1 keV energy was conducted to evaluate contaminant removal effectiveness.