A method for fabricating a vertical GaN power device includes providing a first GaN material having a first conductivity type and forming a second GaN material having a second conductivity type and coupled to the first GaN material to create a junction. The method further includes implanting ions through the second GaN material and into a first portion of the first GaN material to increase a doping concentration of the first conductivity type. The first portion of the junction is characterized by a reduced breakdown voltage relative to a breakdown voltage of a second portion of the junction.