Optimized Transport of Black Phosphorus Top Gate Transistors Using Alucone Dielectrics

In this letter, we demonstrate high performance black phosphorus (BP) top gate transistors using molecular layer deposition (MLD) of high-quality alucone films as top gate dielectrics. Ethylene glycol was used as an oxygen precursor instead of using water or ozone as precursor, which typically results in the oxidation of BP surface. The carrier mobility of BP transistors using the alucone dielectric reaches 216 cm $^{2}/\text{V}\cdot \text{s}$ at room temperature, which is 4.5 times higher than that of with Al 2 O 3 dielectrics using O 3 . The ON current and ON–OFF ratio of the alucone-based transistors are also much higher than the other two types of devices. Meanwhile, we observe a metal-insulator transition in the BP top gate with alucone films, suggesting an excellent interface quality with efficient electro-static gate control. This result shows great potential of MLD for applications in high-quality BP top gate devices.