A vertical gallium nitride (GaN) field effect transistor (FET) device has a selective area implant region comprising an activated impurity configured from a bottom portion of a recessed region and is substantially free from ion implant damage by using an annealing process. A p-type gate region is configured from the selective area implant region, and the recessed region is characterized by a depth configured to physically separate an n+ type source region and the p-type gate region such that a low reverse leakage gate-source p-n junction is achieved. An extended drain region is configured from a portion of an n-type GaN region underlying the recessed region. An n+ GaN region is formed by epitaxial growth directly overlying the backside region of the GaN substrate.