High hole concentration in Mg-doped $a$-plane $Ga1−xInxN$ $(<x<0.30)$ grown on $r$-plane sapphire substrate by metalorganic vapor phase epitaxy

The electrical properties of Mg-doped $a$-plane $Ga1−xInxN$ $(0<x<0.30)$ films on undoped GaN grown by sidewall-epitaxial-lateral overgrowth on $+0.5°$-off $r$-plane sapphire substrates by metalorganic vapor phase epitaxy were systematically investigated. The activation energy of Mg acceptors in $a$-plane $Ga0.83In0.17N$ was as small as 48 meV. Therefore, highly Mg-doped $a$-plane GaInN with a high hole concentration can be realized. A maximum hole concentration of as high as $1.7×1019cm−3$ in $Ga0.71In0.29N$ was reproducibly achieved at room temperature.