High hole concentration in Mg-doped AIN/AIGaN superlattices with high Al content

摘要

We studied hole generation in Mg-doped AlN/Al0.75Ga0.25N superlattices (SLs) with an average Al content of 0.8. High hole concentrations on the order of 10(18) cm(-3) were obtained in the SLs. The temperature dependence of the hole concentration indicated an effective acceptor ionization energy of 40-67 meV, which is much lower than that of Mg-doped Al0.8Ga0.2N alloy (400 meV). The hole concentration increased with increasing SL period thickness and became almost constant at about 30 nm. These results indicate that the band bending caused by strong spontaneous and piezoelectric polarization fields enhances the ionization of the Mg acceptors. (c) 2018 The Japan Society of Applied Physics.