Few-Layered MoS₂ Field-Effect Transistors with a Vertical Channel of Sub-10 nm

Few-layered molybdenum disulfide (MoS₂) has demonstrated promising advantages for the integration of next-generation electronic devices. A vertical short-channel MoS₂ transistor with a channel length of sub-10 nm can be realized using mica as the insulated mesa and MoS₂ flake dry-transferred onto the mica as the channel. A near-perfect symmetrical and fully saturated output characteristic can be obtained for the positive or negative drain-source voltage. This result is attributed to an effective transformation of the drain-source electrode contact from Schottky contact to Ohmic contact via forming gas annealing. The vertical-channel MoS₂ transistor with a channel length of 8.7 nm exhibits excellent electrical characteristics, for example, a negligible hysteresis voltage of 60 mV, an extraordinarily small subthreshold swing of 73 mV/dec, a considerably weakened drain-induced barrier-lowering effect (100 mV/V), and the first-reported intrinsic delay time of 2.85 ps. Moreover, a logic inverter can be realized using the two vertical-channel MoS₂ transistors, with a high voltage gain of 33. Experimental results indicate that the developed method is a potential approach for fabricating MoS₂ transistors with an ultrashort channel and high performance, and consequently, manufacturing MoS₂-based integrated circuits.