Transistors with metal oxide channel material that is in-situ doped for desired charge carrier concentrations. The metal oxide channel material may be deposited by atomic layering of multiple constituent metals with an oxidation of each layer. Such an ALD process may be performed by cyclically depositing a precursor of one of the metals upon a substrate during a deposition phase, and oxidizing the absorbed precursor during an oxidation phase. For a quinary metal oxide, each of three metal precursors may be introduced and oxidized during the ALD process, and charge carrier concentrations may be modulated by further introducing a fourth metal precursor during the ALD process in a manner that disperses this dopant metal within the film at a significantly lower chemical concentration than the other metals.