Small-area (3 X 10 mum emitter) GaN bipolar junction transistors (BJTs) incorporating a superlattice GaN(Mg)/AlGaN(Mg) base contact layer and a selectively regrown emitter were fabricated using a self-aligned dry etch process. The dc current gains were typically 10 at 25 degreesC, and the devices were operated up to emitter current densities of 15 kA cm(-2). The BJTs exhibited high emitter injection efficiency, indicating the presence of a good interface between the initial epi structure and the regrown emitter.