Tunning the carrier concentration n and the position of Fermi-level E F in graphene monolayers has a great impact on the design and fabrication of next generation graphene-based devices. Raman spectral properties of graphene/SiO 2/Si and graphene/Al 2 O 3 are investigated over a wide range of laser power (P L= 1 to 25 m W). The increase in P L results in significant variations in position and half-width of the G-band, allowing the determination of n and E F using nonadiabatic fitting. The initially formed p-type graphene is converted to n-type with increasing P L due to charge transfer to/from graphene with the substrate interfacial defect states and/or redox interactions with environmental gas. Whereas n and E F of the graphene/SiO 2/Si reach saturation at P L= 12 m W, those of graphene/Al 2 O 3 exhibit a monotonic increase before saturating at P L> 21 m W. A noticeable enhancement in graphene quality …