Characterization of AlGaN/GaN p-n diodes with selectively regrown n-AlGaN by metal-organic chemical-vapor deposition and its application to GaN-based bipolar transistors

p-n junctions formed by selective regrowth of n-(Al)GaN on p-GaN were characterized by I–V measurements and secondary-ion-mass spectrometry (SIMS). Regrown p-n diodes of high quality with low leakage currents were achieved, comparable to as-grown GaN p-n diodes, by optimizing the regrowth conditions and structures. SIMS revealed a sharp Mg profile at the regrowth interface. It confirms that these regrown structures are suitable to serve as emitter-base junctions for GaN-based bipolar transistors. This study offers us insight into analyzing n-p-n GaN homojunction bipolar transistors with a current gain of 10 and Al_0.05GaN/GaN heterojunction bipolar transistors with a current gain of 20, demonstrated using emitter regrowth technique.