Improvement of properties for nonpolar a-plane p-AlGaN with Mg-delta doping technique

The Mg-delta-doping technique was employed in the epitaxial growth of the nonpolar a-plane p-AlGaN films on semi-polar r-plane sapphire substrates by metal organic chemical vapor deposition (MOCVD). The structural and electrical properties of the nonpolar a-plane p-AlGaN epi-layers were characterized with secondary ion mass spectroscopy (SIMS), high-resolution X-ray diffraction (HR-XRD), and Hall effect measurement, respectively. The characterization results demonstrated that the crystalline quality, and the efficiency of Mg incorporation in the nonpolar a-plane p-AlGaN films could be improved significantly by optimizing the pulse time of Cp2Mg mass flow in the Mg-delta-doping process. In fact, a hole concentration as high as 1.4×10¹⁸ cm^-3 under an average Mg incorporation density of ~1 × 10¹⁹ cm^-3 was achieved.