A single-crystalline native dielectric for two-dimensional semiconductors with an equivalent oxide thickness below 0.5 nm

Scaling down the size of field-effect transistors in integrated circuits leads to higher speed, lower power consumption and increased integration density, but also results in short-channel effects. Transistors made using high-mobility two-dimensional (2D) semiconductor channels and ultrathin high-κ dielectrics can suppress this effect. However, it is difficult to integrate 2D semiconductors with dielectric layers that have an equivalent oxide thickness below 0.5 nm and low leakage current. Here we report the wafer-scale synthesis of β-Bi2SeO5—a single-crystalline native oxide with a dielectric constant of around 22—via the lithography-compatible ultraviolet-assisted intercalative oxidation of the high-mobility 2D semiconductor Bi2O2Se. We use the approach to create top-gated 2D transistors with sub-0.5-nm-equivalent-oxide-thickness dielectrics that exhibit leakage current below the low-power limit of 0.015 A cm−2 at a gate voltage of 1 V.