Effects of different potential barriers on the structural and optical properties of GaN/AlxGa1-xN/GaN coupled multiquantum wells

Abstract

Coupled multiquantum well structures, GaN/AlxGa 1-xN/GaN bounded by AlxGa1-xN barriers with varying Al content x, are characterized by using high-resolution x-ray diffraction and photoluminescence measurements. It is clearly demonstrated that the structural and optical properties strongly depend on the Al content x. Photoluminescence peaks continue to be redshifted with respect to the bulk GaN band gap with increasing x up to 0.5, but, in turn, become blueshifted beyond this value. This behavior is understood in terms of the different screening effects of the piezoelectric field induced by a strain with increasing Al content. It is found that the strain starts to be relatively relaxed around x=0.5, leading to the reduction in the screening of the piezoelectric field. © 2006 American Institute of Physics.