Taiwanese engineers boost 2D transistor performance

Researchers at Taiwan’s National Yang Ming Chiao Tung University and TSMC Corporate Research have tackled a key obstacle for the adoption of transistors based on 2D materials. Through careful engineering of the atomic interface between a molybdenum disulfide (MoS 2 ) channel and the gate dielectric, the team managed to create switches that combine good carrier mobility with good switching control.

The work addresses a longstanding tradeoff in two-dimensional transistors. Thinner gate dielectrics improve electrostatic control but typically degrade carrier transport because of interface defects. By making the interface an active part of the device, the researchers maintained both strong gate control and efficient electron transport, a combination that’s been difficult to achieve in atomically thin devices.

Credit: NYCU/Nature Electronics

The researchers deposited an epitaxial aluminum layer on monolayer MoS 2 before oxidizing it to form an ultrathin aluminum oxide buffer. That layer promotes uniform growth of a hafnium oxide gate dielectric while reducing electrical disorder at the interface. The resulting top-gate transistors achieved an equivalent oxide thickness of about one nanometer, combined with low leakage current, minimal hysteresis and a maximum transconductance of 0.45 mS μmˆˆ-1ˆˆ.