Methods for fabricating semiconductor devices incorporating an activated p-(Al,In)GaN layer include exposing a p-(Al,In)GaN layer to a gaseous composition of H2 and/or NH3 under conditions that would otherwise passivate the p-(Al,In)GaN layer. The methods do not include subjecting the p-(Al,In)GaN layer to a separate activation step in a low hydrogen or hydrogen-free environment. The methods can be used to fabricate buried activated n/p-(Al,In)GaN tunnel junctions, which can be incorporated into electronic devices.