Improving p-Type Doping in Gallium Nitride through Magnesium Diffusion

Abstract Achieving high p -type doping levels selectively in gallium nitride (GaN) is a nontrivial task. In this work, we present a method for diffusing Mg from a finite source into the GaN layer, creating a highly doped layer with Mg without the need for additional epitaxial growth. Secondary ion mass spectroscopy analysis confirmed a diffusion depth of approximately 50 nm with a surface doping concentration of ~10 22 cm −3 . Confirmation of activation was determined via electrical characterization. This activation of the p -GaN substrate demonstrated a 40% improvement in contact resistance, achieving a specific contact resistance of 7.5 × 10 −4 Ω∙cm 2 . This method offers a promising alternative to ion implantation, which requires high temperature annealing for lattice recovery. In contrast, our approach requires lower thermal energy, overcoming one of the major challenges in doping GaN.