Role of density gradients in the growth dynamics of 2-dimensional MoS2 using liquid phase molybdenum precursor in chemical vapor deposition

The key objective of this work was the comparison of MoS2 2-dimensional monolayer flakes grown by Chemical Vapour Deposition with different density gradients in the liquid precursors solution. Structures grown using solutions with iodixanol or glycerol were characterized by Optical Microscopy, Atomic Force Microscopy, Raman spectroscopy and Photoluminescence. Furthermore, electrical properties of structures were studied by characterizing backgated Field-Effect Transistors fabricated on individual flakes.The fundamental outcome of this study is that there are relevant differences between the structures grown with the two different liquid solutions: MoS2 structures grown with glycerol present a large variability in the lateral size of the sharp-corner triangular structure with a good crystalline quality while the employment of iodixanol (the most used substance) causes a poorer crystalline quality, demonstrated by the presence of nanometric pores, with a more homogeneous sizing of the triangular structures. The poor crystalline quality of the iodixanol samples results in reduced light emission efficiency and lower mobility.