Improvement of properties in nonpolar a-plane p-AlGaN films by Mg-delta doping method

Abstract

The Mg-delta-doping technique was applied for the first time in the epitaxial growth of the non-polar a-plane p-AlGaN films on semi-polar r-plane sapphire substrates by metal organic chemical vapor deposition (MOCVD). The structural, morphological and electrical properties of the non-polar α-plane p-AlGaN epi-layers were characterized by high resolution X-ray diffraction (HR-XRD), atomic force microscopy (AFM) and Hall effect measurement, respectively. A maximum carrier concentration of 1.4×1018 cm−3 with an average Mg incorporation of ∼1×1019 cm−3 was achieved, which is twice higher than that of the uniformly Mg-doped sample due to the suppression of self-compensation effect in the Mg-delta-doped epi-layers. The characterization results also show that not only the crystalline quality but also the surface roughness can be improved by the Mg-delta-doping procedure. This phenomenon can be explained in terms of the blocking of the dislocation by the MgN protrusions that were formed during the Mg-delta doping procedure.