Van der Waals Epitaxial Trilayer MoS<sub>2</sub> Crystals for High‐Speed Electronics
Xuefei Li, Zhenfeng Zhang, Tingting Gao, Xinhang Shi, Chengru Gu, Yanqing Wu
Abstract
Abstract Two‐dimensional MoS 2 field‐effect transistors (FETs) have great potential for next‐generation electronics due to their excellent electronic properties with an atomic thin channel. However, multiple challenges exist for the monolayer MoS 2 channel, including interface scattering and ohmic contact. In this work, well‐controlled trilayer MoS 2 with high mobility and large single crystals is successfully grown on soda‐lime glass substrates using chemical vapor deposition, with a lateral size of up to 148 µm, which is the largest reported size to date. A record high on/off ratio of ≈10 12 and a high carrier mobility of 62 cm 2 V −1 s −1 of trilayer MoS 2 FETs are demonstrated, showing notable advantages compared with the monolayer counterpart. The long‐standing issue of monolayer MoS 2 performance degradation from physical vapor deposited metal contact can be mitigated by the trilayer MoS 2 channel, achieving the lowest contact resistance of 350 Ω µm using the common method of e‐beam evaporated Ni. Moreover, 40‐nm channel‐length trilayer MoS 2 FETs using ultrathin HfLaO dielectrics exhibit a high current of 589 µA µm −1 at a supply voltage of 1 V at room temperature, which increases to 1162 µA µm −1 at 4.3 K, the highest among those using commonly evaporated metal. Record high electron saturation velocity of 4.2 × 10 6 cm s −1 can be achieved at room temperature.