  Monolayer molybdenum disulphide (MoS$_2$) is a promising two-dimensional (2D)
material for nanoelectronic and optoelectronic applications. The large-area
growth of MoS$_2$ has been demonstrated using chemical vapor deposition (CVD)
in a wide range of deposition temperatures from 600 {\deg}C to 1000 {\deg}C.
However, a direct comparison of growth parameters and resulting material
properties has not been made so far. Here, we present a systematic experimental
and theoretical investigation of optical properties of monolayer MoS$_2$ grown
at different temperatures. Micro-Raman and photoluminescence (PL) studies
reveal observable inhomogeneities in optical properties of the as-grown single
crystalline grains of MoS$_2$. Close examination of the Raman and PL features
clearly indicate that growth-induced strain is the main source of distinct
optical properties. We carry out density functional theory calculations to
describe the interaction of growing MoS$_2$ layers with the growth substrate as
the origin of strain. Our work explains the variation of band gap energies of
CVD-grown monolayer MoS$_2$, extracted using PL spectroscopy, as a function of
deposition temperature. The methodology has general applicability to model and
predict the influence of growth conditions on strain in 2D materials.
