Incorporation of metallic quantum dots (e.g., silver bromide (AgBr) films) into the source and drain regions of a MOSFET can assist in controlling the transistor performance by tuning the threshold voltage. If the silver bromide film is rich in bromine atoms, anion quantum dots are deposited, and the AgBr energy gap is altered so as to increase Vt. If the silver bromide film is rich in silver atoms, cation quantum dots are deposited, and the AgBr energy gap is altered so as to decrease Vt. Atomic layer deposition (ALD) of neutral quantum dots of different sizes also varies Vt. Use of a mass spectrometer during film deposition can assist in varying the composition of the quantum dot film. The metallic quantum dots can be incorporated into ion-doped source and drain regions. Alternatively, the metallic quantum dots can be incorporated into epitaxially doped source and drain regions.