Embodiments of the present disclosure provide wet process based methods for modifying threshold value (Vt) of high-k metal gate using self-assembled monolayer (SAM) on dedicated transistor. In one embodiment, the method includes forming a gate structure over a substrate, the gate structure comprising a gate dielectric layer, a barrier layer formed over the gate dielectric layer, and an oxide layer formed over the barrier layer, and forming a self-assembled monolayer on the oxide layer by exposing the oxide layer to an aqueous solution containing metal oxides in a metal dissolving acid.