A method and system are disclosed for doping a semiconductor substrate. In one embodiment, the method comprises forming a carbon free layer of phosphoric acid on a semiconductor substrate, and diffusing phosphorous from the layer of phosphoric acid in the substrate to form an activated phosphorous dopant therein. In an embodiment, the semiconductor substrate is immersed in a solution of a phosphorous compound to form a layer of the phosphorous compound on the substrate, and this layer of phosphorous is processed to form the layer of phosphoric acid. In an embodiment, this processing may include hydrolyzing the layer of the phosphorous compound to form the layer of phosphoric acid. In one embodiment, an oxide cap layer is formed on the phosphoric acid layer to form a capped substrate. The capped substrate may be annealed to diffuse the phosphorous in the substrate and to form the activated dopant.