ALBERT

Description: Transistors with exfoliated two-dimensional (2D) materials on a SiO 2 /Si substrate have been applied and have been proven effective in a wide range of applications, such as circuits, memory, photodetectors, gas sensors, optical modulators, valleytronics, and spintronics. However, these devices usually suffer from limited gate control because of the thick SiO 2 gate dielectric and the lack of reliable transfer method. We introduce a new back-gate transistor scheme fabricated on a novel Al 2 O 3 /ITO (indium tin oxide)/SiO 2 /Si "stack" substrate, which was engineered with distinguishable optical identification of exfoliated 2D materials. High-quality exfoliated 2D materials could be easily obtained and recognized on this stack. Two typical 2D materials, MoS 2 and ReS 2 , were implemented to demonstrate the enhancement of gate controllability. Both transistors show excellent electrical characteristics, including steep subthreshold swing (62 mV dec –1 for MoS 2 and 83 mV dec –1 for ReS 2 ), high mobility (61.79 cm 2 V –1 s –1 for MoS 2 and 7.32 cm 2 V –1 s –1 for ReS 2 ), large on/off ratio (~10 7 ), and reasonable working gate bias (below 3 V). Moreover, MoS 2 and ReS 2 photodetectors fabricated on the basis of the scheme have impressively leading photoresponsivities of 4000 and 760 A W –1 in the depletion area, respectively, and both have exceeded 10 6 A W –1 in the accumulation area, which is the best ever obtained. This opens up a suite of applications of this novel platform in 2D materials research with increasing needs of enhanced gate control.