Zinc Oxide (ZnO) has recently attracted considerable attention because of its potential applications in the blue and the UV spectral range. To now, (Zn,Mg)O/ZnO heterostructures have been grown in a $c$-orientation. The growth of non-polar layers along the a direction [11={2}0] has been proposed to avoid any built-in electric fields in the $c$-direction. A series of $A$-plane (11={2}0) ZnO quantum wells (QWs) and multiple QWs embedded in (Zn,Mg)O barriers were grown. After the structural and the optical characterizations of the (Zn,Mg)O buffer layers, we compared the PL emission of $a$-oriented and $c$-oriented QWs and MQWs. We demonstrated that the $a$-oriented quantum wells exhibited confinement, but no indication of the quantum confined Stark effect was observed, in contrast with $c$-oriented heterostructures.

Keywords: Molecular beam epitaxy, ZnO, Oxides, Semiconducting II-VI materials