The evolution of near-interfacial defects from upon thermal annealing was studied by photoluminescence, deep level transient spectroscopy, and secondary ion mass spectroscopy. It was found that all the results were strongly connected and that they point to the direction that Zn out-diffused from ZnO to the oxide layer during annealing and created deep-level defects near to the interfacial region. These defects reduced the band-edge emission and increase the deep level emission at 2.37eV. The study showed that the oxide/ZnO interface was relatively fragile and caution must be taken for making metal-oxide-ZnO based transistors and light emitting diodes.

Studies of Oxide/ZnO Near-Interfacial Defects by Photoluminescence and Deep Level Transient Spectroscopy. R.S.Wang, Q.L.Gu, C.C.Ling, H.C.Ong: Applied Physics Letters, 2008, 92[4], 042105