Development of advanced power electronics with increased functionality, efficiency, reliability, and reduced form factor are required in an increasingly electrified world economy. Fast switching power semiconductor devices are key to increasing the efficiency and reducing the size of power electronic systems. However, the prevailing power semiconductor devices, based on silicon, are fast approaching their performance limits. Wide band-gap (WBG) semiconductors, such as gallium nitride (GaN) and silicon carbide (SiC), with their superior electrical properties are enabling a new generation of power semiconductor devices that offer enormous energy efficiency gains in a wide range of applications. The U.S. Department of Energy’s Advanced Research Projects Agency-Energy (ARPA-E) SWITCHES program identified the lack of a viable selective area doping processes as a major barrier to fabricating vertical GaN power electronic devices. The most obvious approaches, such as ion implantation with activation or selective area diffusion of dopants, have not produced p-type regions or satisfactory p-n junctions. Furthermore, selective area etch and regrowth approaches have resulted in poor electrical performance not sufficient for power electronic applications. To address this challenge ARPA-E launched the PNDIODES program to develop transformational advances and mechanistic understanding in the process of selective area doping in the group III-Nitride wide-bandgap semiconductor material systems. The progress and challenges of selective area doping faced by the SWITCHES program is reviewed along with the mechanistic understanding being developed under the PNDIODES program. Material and processing challenges, including reliability concerns, for GaN power devices are also described. A glimpse into the future trends in device development and commercialization is offered.