Among the transition metal dichalcogenides, single layer MoS2 has drawn great attention due to its direct bandgap of approximately 1.9 eV at room temperature, exhibiting extremely high excitonic photoluminescence in the visible range, making it a promising material for opto-electronic applications. In this work, we synthesized MoS2 on a Si/SiO2 substrate using a single-step atmospheric pressure chemical vapor deposition process, successfully yielding bilayer to few layered MoS2 films. The layer dependence of the as-grown MoS2 layers was analyzed from the peak energy difference (Δ) between the in-plane (E2g) and out-of-plane (A1g) phonon modes in the Raman spectra to quantify the specific number of layers within the MoS2 flake (2–15 layers). Room-temperature photoluminescence characteristics of the excitonic emission exhibited a redshift in energy by 0.04 eV as the number of layers increased in MoS2. An increase in the number of layers exhibited a decreasing dispersion of trion binding energy from a standardized fitting procedure of the PL spectra under appropriate boundary conditions. Henceforth, we observe a thickness dependent inversely related interplay between trion binding energy and electron density (n) due to defects in MoS2, which is crucial for future opto-electronic applications.
