Methods of fabricating a semiconductor device include providing a semiconductor substrate that includes a plurality of epitaxial layers, including a channel layer and a permanent cap over the channel layer, where the permanent cap defines an upper surface of the semiconductor substrate, and forming a sacrificial cap over the permanent cap in an active region of the device, where the sacrificial cap comprises a semiconductor material that includes aluminum. The method also includes forming one or more current carrying regions (e.g., source and drain regions) in the semiconductor substrate in the active region of the device by performing an ion implantation process to implant ions through the sacrificial cap, and into the semiconductor substrate, completely removing the sacrificial cap in the active region of the device, while refraining from removing the permanent cap, and forming one or more current carrying contacts over the one or more current carrying regions.