Migration and luminescence enhancement effects of deuterium in ZnO/ZnCdO quantum wells

ZnO/ZnCdO/ZnO multiple quantum well samples grown on sapphire substrates by molecular beam epitaxy and annealed in situ were exposed to D-2 plasmas at 150 degrees C. The deuterium showed migration depths of similar to 0.8 mu m for 30 min plasma exposures, with accumulation of H-2 in the ZnCdO wells. The photoluminescence (PL) intensity from the samples was increased by factors of 5 at 5 K and similar to 20 at 300 K as a result of the deuteration, most likely due to passivation of competing nonradiative centers. Annealing up to 300 degrees C led to increased migration of H-2 toward the substrate but no loss of deuterium from the sample and little change in the PL intensity. The initial PL intensities were restored by annealing at >= 400 degrees C as H-2 was evolved from the sample (similar to 90% loss by 500 degrees C). By contrast, samples without in situ annealing showed a decrease in PL intensity with deuteration. This suggests that even moderate annealing temperatures lead to degradation of ZnCdO quantum wells. (c) 2008 American Institute of Physics.