Semiconductor device structures and related fabrication methods are provided. An exemplary semiconductor device structure includes a body region of semiconductor material having a first conductivity type, a source region of semiconductor material having a second conductivity type within the body region, a junction isolation region of semiconductor material having the second conductivity type, a drain region of semiconductor material having the second conductivity type, and first and second drift regions of semiconductor material having the second conductivity type. The first drift region resides laterally between the drain region and the junction isolation region, the junction isolation region resides laterally between the first drift region and the second drift region, and the second drift region resides laterally between the body region and the junction isolation region.