In this work, an AlN-ZnO/ZnO/AlN-ZnO double heterojunction (DH) structure prepared using the cosputtering technology was deposited onto the p-type GaN epitaxial layer. The indiffusion of the oxygen atoms to the p-GaN epilayer was obstructed as the cosputtered AlN-ZnO film inset between n-ZnO/p-GaN interface. The near-ultraviolet (UV) emission from this ZnO/GaN-based light emitting diode (LED) was greatly improved as compared to an n-type ZnO film directly deposited onto the p-GaN epilayer. Meanwhile, the native defects in the n-ZnO layer associated with the green luminescence was less likely to form while it was sandwiched by the cosputtered AlN-ZnO film. As the thickness of the active n-ZnO layer in the DH structure reached 10 nm, the near-band-edge (NBE) emission became the predominated luminescence over the resulting LED spectrum.

In this study, a thin silver (Ag) layer was evaporated onto the anatase-titanium oxide (TiOx) film. This structure was then annealed at various temperatures under nitrogen ambient to realize the Ag nanoparticles formed on the TiOx surface. The photocatalytic activities of these TiOx/Ag structures to decompose pollutants were determined from the rate constant while they were applied to decolorize the methylene blue (MB) solution in the presence of the UV light irradiation. According to the investigations on their surface bond configurations, the Ag nanoparticles were favorable for the transformation of the Ti4+ into the Ti3+ state in the TiOx film, which functioned to prohibit the recombination of the photogenerated electron-hole-pairs on the TiOx surface. The exposed TiOx surface distributed over the 500 °C-annealed TiOx/Ag structure performed an increase of about 40% in the rate constant compared to the individual TiOx film. Moreover, this surface morphology composed of the anatase-TiOx structures and Ag nanoparticles which was abundant in the oxide-related radical and Ag+ chemical state also showed a perfect antibacterial efficiency against Escherichia coli.