A transistor device having non-alloyed ohmic contacts formed by a process that improves the contact morphology and reduces metal spiking into the semiconductor layers. During fabrication, a regrowth mask is deposited on the semiconductor device. A portion of the regrowth mask and the epitaxial semiconductor layers is removed, defining areas for selective regrowth of a highly-doped semiconductor material. The remaining portion of the regrowth mask forms a regrowth mask residual layer. After regrowth, ohmic contacts are formed on the regrowth structures without the use of a high-temperature annealing process. The regrowth mask residual layer does not need to be removed, but rather remains on the device throughout fabrication and can function as a passivation layer and/or a spacer layer.