Embodiments herein describe techniques for a semi-conductor device comprising a channel having a first semiconductor material; a source contact coupled to the channel, comprising a first Heusler alloy; and a drain contact coupled to the channel, comprising a second Heusler alloy. The first Heusler alloy is lattice-matched to the first semiconductor material within a first predetermined threshold. A first Schottky barrier between the channel and the source contact, and a second Schottky barrier between the channel and the drain contact are negative, or smaller than another predetermined threshold. The source contact and the drain contact can be applied to a strained silicon transistor, an III-V transistor, a tunnel field-effect transistor, a dichalcogenide (MX2) transistor, and a junctionless nanowire transistor.