a catalyst particle on a substrate is exposed to reactants containing a semiconductor material in a reactor . an intrinsic semiconductor nanowire having constant lateral dimensions is grown at a low enough temperature so that pyrolysis of the reactant is suppressed on the sidewalls of the intrinsic semiconductor nanowire . once the intrinsic semiconductor nanowire grows to a desired length , the temperature of the reactor is raised to enable pyrolysis on the sidewalls of the semiconductor nanowire , and thereafter dopants are supplied into the reactor with the reactant . a composite semiconductor nanowire having an intrinsic inner semiconductor nanowire and a doped semiconductor shell is formed . the catalyst particle is removed , followed by an anneal that distributes the dopants uniformly within the volume of the composite semiconductor nanowire , forming a semiconductor nanowire having constant lateral dimensions and a substantially uniform doping .