  The growth of large crystallite continuous monolayer materials like
molybdenum disulfide (MoS$_2$) with desired morphology via chemical vapor
deposition (CVD) remains a challenge. In CVD, the complex interplay of various
factors like growth temperature, precursors, and nature of the substrate
decides the crystallinity, crystallite size, and coverage area of the grown
MoS$_2$ monolayer. In the present work, we report about the role of weight
fraction of molybdenum trioxide (MoO$_3$), Sulfur, and carrier gas flow rate
towards nucleation and monolayer growth. The concentration of MoO$_3$ weight
fraction has been found to govern the self-seeding process and decides the
density of nucleation sites affecting morphology and coverage area. Carrier gas
flow of 100 sccm argon results into large crystallite continuous films with
lower coverage area (70 %), while the flow rate of 150 sccm results into 92 %
coverage area with reduced crystallite size. Through systematic variation of
experimental parameters, we have established the recipe for the growth of large
crystallite atomically thin MoS$_2$ suitable for optoelectronic devices.
