Interfacial Band Engineering of MoS 2 /Gold Interfaces Using Pyrimidine‐Containing Self‐Assembled Monolayers: Toward Contact‐Resistance‐Free Bottom‐Contacts

Bottom‐contact architectures with common electrode materials such as gold are crucial for the integration of 2D semiconductors into existing device concepts. The high contact resistance to gold—especially for bottom contacts—is, however, a general problem in 2D semiconductor thin‐film transistors. Pyrimidine‐containing self‐assembled monolayers on gold electrodes are investigated for tuning the electrode work functions in order to minimize that contact resistance. Their frequently ignored asymmetric and bias‐dependent nature is recorded by Kelvin probe force microscopy through a direct mapping of the potential drop across the channel during device operation. A reduction of the contact resistances exceeding two orders of magnitude is achieved via a suitable self‐assembled monolayer, which vastly improves the overall device performance.