Growth and characterization of A-plane ZnO and ZnCoO based heterostructures

Non polar ZnO and (Zn, Co)O layers were successfully grown on (11̄02) sapphire (R-plane sapphire). The growth process was shown to directly influence the surface morphology as well as the strain state in (112̄0) ZnO (A-plane ZnO). The dominant defect lines seen in photoluminescence were due to basal stacking faults as demonstrated by means of selective photoluminescence and transmission electron microscopy. We present a novel method for growing high quality A-plane ZnO by inserting a (Zn, Co)O thin buffer layer, which strongly reduced the surface roughness. Finally (Zn, Mg)O/ZnO quantum well structures were grown on such a buffer layer. These quantum wells exhibited no intrinsic quantum confined Stark effect. PACS 81.05.Dz; 81.15.Hi; 78.67.Hc; 68.65.Fg