Implementations of an ohmic contact for a gallium nitride (GaN) device may include: a first layer including aluminum coupled directly with the GaN device; the GaN having a heterostructure with an undoped GaN channel and a semi-insulating aluminum gallium nitride (AlGaN) barrier, all the foregoing operatively coupled with a substrate; a second layer including titanium coupled over the first layer; and a third layer including an anti-diffusion material coupled with the second layer. The passivation layer may be coupled between the AlGaN barrier and the first layer of the ohmic contact. The passivation layer may surround the ohmic contact.