A method of forming a semiconductor structure having a substrate is disclosed. The semiconductor structure includes a first layer formed in contact with the substrate. The first layer made of a first III-V semiconductor material selected from GaN, GaAs and InP. A second layer is formed on the first layer. The second layer made of a second III-V semiconductor material selected from AlGaN, AlGaAs and AlInP. An interface is between the first layer and the second layer forms a carrier channel. An insulating layer is formed on the second layer. Portions of the insulating layer and the second layer are removed to expose a top surface of the first layer. A metal feature is formed in contact with the carrier channel and the metal feature is annealed to form a corresponding intermetallic compound.