A method for locally controlling the stoichiometry of an epitaxially deposited layer on a semiconductor substrate is provided. The method includes directing a first reactant gas and a doping gas across a top surface of a semiconductor substrate and directing a drive gas and a second reactant gas against the substrate separately from the first reactant gas in a manner that rotates the substrate while introducing the second reactant gas at an edge of the substrate to control each reactant separately, thereby compensating and controlling depletion effects and improving doping uniformity in resulting epitaxial layers on the substrate.