Improved Surface Characteristics and Contact Performance of Epitaxial p-AlGaN by a Chemical Treatment Process

The comparative study of epitaxial 380-nm-thick p-Al_0.91Ga_0.909 N materials without and with special surface chemical treatment is systematically carried out. After the treatment process, the deep level luminous peak in the 10K photoluminescence spectrum is eliminated due to the decrease of surface nitrogen vacancy V_N related defective sites, while the surface root-mean-square roughness in atomic force microscopy measurement is decreased from 0.395nm to 0.229nm by such a surface preparation method. Furthermore, the performance of surface contact with Ni/Au bilayer metal films is obviously improved with the reduction of the Schottky barrier height of 55meV. The x-ray photoelectron spectroscopy (XPS) results show a notable surface element content change after the treatment which is considered to be the cause of the above-mentioned surface characteristics improvement.