Abstract:
Implantation with low-energy (80 keV) oxygen ions and subsequent rapid
thermal annealing at 800 ◦C are used to induce intermixing in a stack of 19
ZnO/Zn0.7Mg0.3O multiple quantum wells grown on sapphire by molecular
beam epitaxy. Large blue shifts of more than 300 meV have been observed
for doses up to 1 × 1016 cm−2, with no observation of saturation. This
process is driven by the creation of defects by implantation which encourage
the diffusion of Mg from the barrier layers into the ZnO quantum wells.
Although defects are introduced during the implantation process, good
recovery of the cathodoluminescence is seen following rapid thermal
annealing. The Zn–Mg interdiffusion in this system has also been calculated
for the corresponding ion doses, and the diffusion coefficient extracted. This
study has significant implications for band gap engineering of ZnO/ZnMgO
optoelectronic devices.
