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Two-dimensional (2D) materials possess unique thickness- and lateral-size-dependent properties. Many efforts have been devoted to obtaining 2D materials with narrow structure heterogeneity while it is still challenging to independently control their thickness and lateral size, limiting their widespread applications. Here, we develop a three-step method which achieves independent thickness and lateral size sorting of 2D materials. Taking 2D h-BN flakes as an example, their thickness and lateral size are independently sorted to different fractions with thicknesses smaller than 6 nm. In addition, the 2D h-BN flakes possess narrow distributions of both thickness and lateral size. We further develop a force field extraction method and achieve scalable size sorting of 2D h-BN, which is universal for sorting other 2D materials including MoS2 and graphene oxide. This work reports an effective method to produce structure homogenous 2D materials and will help fundamental studies and applications of 2D materials where thickness and lateral size are of concern.

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) have drawn intensive attention due to their ultrathin feature with excellent electrostatic gating capability, and unique thickness-dependent electronic and optical properties. Controlling the thickness and doping of 2D TMDCs are crucial toward their future applications. Here, we report an effective HAuCl4 treatment method and achieve simultaneous thinning and doping of various TMDCs in one step. We find that the HAuCl4 treatment not only thins thick MoS2 flakes into few layers or even monolayers, but also simultaneously tunes MoS2 into p-type. The effects of various parameters in the process have been studied systematically, and an Au intercalation assisted thinning and doping mechanism is proposed. Importantly, this method also works for other typical TMDCs, including WS2, MoSe2 and WSe2, showing good universality. Electrical transport measurements of field-effect transistors (FETs) based on MoS2 flakes show a big increase of On/Off current ratios (from 102 to 107) after the HAuCl4 treatment. Meanwhile, the subthreshold voltages of the MoS2 FETs shift from −60 to +27 V after the HAuCl4 treatment, with a p-type doping behavior. This study provides an effective and simple method to control the thickness and doping properties of 2D TMDCs, paving a way for their applications in high performance electronics and optoelectronics.