Utility of ZnGa₂O₄ Nanoparticles Obtained Hydrothermally for Preparation of GaN:ZnO Solid Solution Nanoparticles and Transparent Films

GaN:ZnO solid solution nanoparticles and films were synthesized by using ZnGa₂O₄ nanoparticles with a particle size of below 25 nm obtained hydrothermally as a precursor. Nitridation of powder ZnGa₂O₄ nanoparticles led to the formation of GaN:ZnO nanoparticles. The nitrided samples have higher specific surface area than those obtained by conventional method, which induces higher photocatalytic NO_x decomposition activity. In addition, a transparent coating film with ZnGa₂O₄ nanoparticles was converted to GaN:ZnO film after nitridation. The nitrided film absorbs UV and blue light and is transparent for light of wavelength over 500 nm (the transmittance is over 90 %). This means that the nitridation does not lead to the formation of scattering domains by the large-size particles and cracks. This method for film preparation is much cheaper than conventional CVD and sputtering processes. These results strongly suggest the utility of ZnGa₂O₄ nanoparticles not only for the formation of GaN:ZnO solid solution nanoparticles with high specific surface area but also for the preparation of transparent GaN:ZnO solid solution films.