Epitaxial Growth of Step-Like Cr S Lateral Homojunctions Towards Versatile Conduction Polarities and Enhanced Transistor Performances.

For expanding the applications of 2D transition metal dichalcogenides (TMDCs), integrating functional devices with diverse conduction polarities in the same parent material is a very promising direction. Improving the contact issue at the metal-semiconductor interface also holds fundamental significance. To achieve these concurrently, step-like Cr S vertical stacks with varied thicknesses are achieved via a one-step chemical vapor deposition (CVD) method route. Various types of 2D Cr S lateral homojunctions are thus naturally evolved, that is, p -ambipolar/n, p/ambipolar, ambipolar/n, and n -ambipolar/n junctions, allowing the integration of diverse conduction polarities in single Cr S homojunctions. Significantly, on-state current density and field-effect mobility of the thinner 2D Cr S flakes stacked below are detected to be ≈5 and ≈6 times increased in the lateral homojunctions, respectively. This work should hereby provide insights for designing 2D functional devices with simpler structures, for example, multipolar field-effect transistors, photodetectors, and inverters, and provide fundamental references for optimizing the electrical performances of 2D materials related devices.