Improved complementary doping methods are described herein. The complementary doping methods generally involve inducing a first and second chemical reaction in at least a first and second portion, respectively, of a dopant source, which has been disposed on a thin film of a semiconductor or semimetal material. The chemical reactions result in the introduction of an n-type dopant, a p-type dopant, or both from the dopant source to each of the first and second portions of the thin film of the semiconductor or semimetal. Ultimately, the methods produce at least one n-type and at least one p-type region in the thin film of the semiconductor or semimetal.