There are disclosed herein various implementations of a semiconductor device including a group III-V layer situated over a substrate, and a phase-change material (PCM) radio frequency (RF) switch situated over the group III-V layer. The PCM RF switch couples a group III-V transistor situated over the group III-V layer to one of an integrated passive element or another group III-V transistor situated over the group III-V layer. The PCM RF switch includes a heating element transverse to the PCM, the heating element underlying an active segment of the PCM. The PCM RF switch is configured to be electrically conductive when the active segment of the PCM is in a crystalline state, and to be electrically insulative when the active segment of the PCM is in an amorphous state.