Ultrathin Van der Waals Lanthanum Oxychloride Dielectric for 2D Field‐Effect Transistors

Abstract Downsizing silicon‐based transistors can result in lower power consumption, faster speeds, and greater computational capacity, although it is accompanied by the appearance of short‐channel effects. The integration of high‐mobility 2D semiconductor channels with ultrathin high dielectric constant (high‐κ) dielectric in transistors is expected to suppress the effect. Nevertheless, the absence of a high‐κ dielectric layer featuring an atomically smooth surface devoid of dangling bonds poses a significant obstacle in the advancement of 2D electronics. Here, ultrathin van der Waals (vdW) lanthanum oxychloride (LaOCl) dielectrics are successfully synthesized by precisely controlling the growth kinetics. These dielectrics demonstrate an impressive high‐κ value of 10.8 and exhibit a remarkable breakdown field strength (E_bd) exceeding 10 MV cm⁻¹. Remarkably, the conventional molybdenum disulfide (MoS₂) field‐effect transistor (FET) featuring a dielectric made of LaOCl showcases an almost negligible hysteresis when compared to FETs employing alternative gate dielectrics. This can be attributed to the flawlessly formed vdW interface and excellent compatibility established between LaOCl and MoS₂. These findings will motivate the further exploration of rare‐earth oxychlorides and the development of more‐than‐Moore nanoelectronic devices.