Contacts for semiconductor devices and methods of making thereof are disclosed. A method comprises forming a first layer on a semiconductor, the first layer comprising one or more metals; forming a second layer on the first layer, the second layer comprising the one or more metals, nitrogen and oxygen; and heating the first and second layer such that oxygen migrates from the second layer into the first layer and the first layer comprises a sub-stoichiometric metal oxide after heating. Exemplary embodiments use transition metals such as Ti in the first layer. After heating there is a sub-stoichiometric oxide layer of about 2.5 nm thickness between a metal nitride conductor and the semiconductor. The specific contact resistivity is less than about 7×10−9 Ω·cm2.