High p-conductivity in AlGaN enabled by polarization field engineering
Shashwat Rathkanthiwar, Pramod Reddy, Baxter Moody, Cristyan Quiñones-García, Pegah Bagheri, Dolar Khachariya, Rafael Dalmau, Seiji Mita, Ronny Kirste, Ramón Collazo, Zlatko Sitar
Abstract
High p-conductivity (0.7 Ω−1 cm−1) was achieved in high-Al content AlGaN via Mg doping and compositional grading. A clear transition between the valence band and impurity band conduction mechanisms was observed. The transition temperature depended strongly on the compositional gradient and to some degree on the Mg doping level. A model is proposed to explain the role of the polarization field in enhancing the conductivity in Mg-doped graded AlGaN films and the transition between the two conduction types. This study offers a viable path to technologically useful p-conductivity in AlGaN.