Investigation of optical and electrical properties of Mg-doped p-In xGa 1−xN, p-GaN and p-Al yGa 1−yN grown by MOCVD

Abstract

Mg-doped p-In x Ga 1− x N ( 0 ⩽ x ⩽ 0.045 ) and p-Al y Ga 1− y N ( 0 ⩽ y ⩽ 0.095 ) layers were grown on sapphire substrates by metalorganic chemical vapor deposition (MOCVD). We investigated the activation energy of Mg dopant in Mg-doped p-InGaN, p-GaN and p-AlGaN, as confirmed by PL emission lines of the band to impurity transition of free electrons with neutral Mg acceptors. Under the same Mg doping concentration of 2×10 19 cm −3, the band to acceptor emission energy E(e −, A 0) of Mg-doped p-type In x Ga 1− x N decreased with increasing the In composition, whereas the E(e −, A 0) of Mg-doped p-type Al y Ga 1− y N increased with Al composition. It suggests that the activation energy of Mg dopant has proportional relationship with the band gap energy of III-nitrides. The Hall measurements showed that the hole concentration of Mg-doped p-type In 0.045Ga 0.955N was 1.3×10 18 cm −3 and that of Mg-doped p-type Al 0.075Ga 0.925N was 8.9×10 16 cm −3.