The present disclosure generally relates to integrated devices with a conductive barrier structure. In an example, a semiconductor device includes a substrate, a conductive barrier structure, a channel layer, a barrier layer, a gate, and a conductive structure. The substrate is of a first semiconductor material. The conductive barrier structure is on the substrate. The channel layer is of a second semiconductor material and is on the conductive barrier structure. The barrier layer is on the channel layer, and the channel layer is between the barrier layer and the conductive barrier structure. The gate is over the barrier layer opposing the channel layer. The conductive structure is electrically coupled between the conductive barrier structure, the channel layer, and the barrier layer.