Optical characterization of AlGaN/GaN quantum disc tructures in single nanowires
Résumé
We report a systematic study of the luminescence properties of AlxGa1-xN/GaN single and multi quantum disc structures in single nanowires with Al fraction xAl varying from 0.05 to 1. These quantum structures are situated on the top of GaN nanowires grown in the polar [0001] direction. Nanowires are synthesized by Plasma Assisted Molecular Beam Epitaxy under nitrogen rich growth conditions at a substrate temperature of T = 780 °C on Si (111) substrates. The PL energy of single and multiquantum disc systems is explained in terms of Al content in the barriers, band bending at the upper polar surface, and strain relaxation in the heterostructure region.