Growth of Large-Area 2D MoS₂ Arrays at Pre-Defined Locations Using Stencil Mask Lithography.

The growth of MoS2 layers of desired dimensions at predefined locations is essential for fabricating opto-electronic devices based solely on MoS2 or on hetero-structures based on MoS2. Here we present a new route for patterned growth of MoS2 by combining radio frequency (RF) magnetron sputtering, stencil mask lithography and vapour phase sulfurization. The present method does not involve chemical etchants and organic photoresist and hence provides a simplified process of achieving MoS2 patterns. Here, the control over the number of layers (mono, few and bulk) of MoS2 is achieved by varying the thickness of Mo films. The statistical variation in thickness i.e., number of MoS2 layers within the individual patterns is investigated from Raman mappings which revealed the uniform growth of 3-4 MoS2 layers. From Kelvin probe force microscopy, the surface potential values of MoS2 patterns lie in the range -350 to -370 mV, which is consistent with 2D MoS2 layer with thickness of 3-4 layers. The surface potential analysis across individual patterns indicates weakly n-type doping of few layers MoS2 with Fermi level located ~0.83-0.85 eV below the conduction band edge.