Van der Waals Epitaxial Trilayer MoS2 Crystals for High-Speed Electronics

Two-dimensional MoS2 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 MoS2 channel, including interface scattering and ohmic contact. In this work, well-controlled trilayer MoS2 with high mobility and large single crystals is successfully grown on soda-lime glass substrates using chemical vapor deposition (CVD), with a lateral size of up to 148 mu m, which is the largest reported size to date. A record high on/off ratio of approximate to 10(12) and a high carrier mobility of 62 cm(2) V-1 s(-1) of trilayer MoS2 FETs are demonstrated, showing notable advantages compared with the monolayer counterpart. The long-standing issue of monolayer MoS2 performance degradation from physical vapor deposited metal contact can be mitigated by the trilayer MoS2 channel, achieving the lowest contact resistance of 350 ohm mu m using the common method of e-beam evaporated Ni. Moreover, 40-nm channel-length trilayer MoS2 FETs using ultrathin HfLaO dielectrics exhibit a high current of 589 mu A mu m(-1) at a supply voltage of 1 V at room temperature, which increases to 1162 mu A mu m(-1) at 4.3 K, the highest among those using commonly evaporated metal. Record high electron saturation velocity of 4.2 x 10(6) cm s(-1) can be achieved at room temperature.