Semiconductor devices and methods for making semiconductor devices are disclosed herein. A method configured in accordance with a particular embodiment includes forming a stack of semiconductor materials from an epitaxial substrate, where the stack of semiconductor materials defines a heterojunction, and where the stack of semiconductor materials and the epitaxial substrate further define a bulk region that includes a portion of the semiconductor stack adjacent the epitaxial substrate. The method further includes attaching the stack of semiconductor materials to a carrier, where the carrier is configured to provide a signal path to the heterojunction. The method also includes exposing the bulk region by removing the epitaxial substrate.