Do Contact Effects Always Mean Slow? Fast-Switching Contact-Controlled Multimodal Transistors

We investigate a mechanism for greatly improving switching speed in contact-controlled thin-film transistors (TFTs), which have persistently performed much slower than Ohmic contact variants. Separating the mechanisms for charge injection and conduction can result in transient settling times two orders of magnitude lower than existing contact-controlled devices [e.g., source-gated transistor (SGT)] and even lower than in Ohmic contact TFTs for a given drain current. High-speed operation is not necessarily only promoted by the well-studied reduction in contact resistance, but rather by the presence of a pre-charged accumulation layer in the source region. These findings greatly expand the applicability of contact-controlled transistors.