The fabrication of surface nano-roughened zinc oxide (ZnO) is demonstrated by using a zinc/air fuel cell based chemical reactor. The chemical reaction creates the hydroxyl near the Zn and randomizes the pores with accumulated hydroxyls, which causes Zn to be oxidized to form thick and nano-roughened ZnO upon Zn anode or to be transformed into a soluble complex zincate ion in the excess electrolyte. Furthermore, controlling the quantity of (Zn(OH)2) and [Zn(OH)4]2− can significantly decrease the defect-related emission and blue-shift PL spectra to the UV range.

GaN and InGaN layers were grown on annealed 20 and 50nm Al2O3/ZnO substrates by metalorganic chemical vapor deposition (MOCVD). GaN was only observed by high resolution x-ray diffraction (HRXRD) on 20 nm Al2O3/ZnO substrates. Room temperature photoluminescence (RT-PL) showed the red shift of the GaN near band-edge emission, which might be from oxygen incorporation forming a shallow donor-related level in GaN. HRXRD measurements revealed that (0002) InGaN layers were also successfully grown on 20nm Al2O3/ZnO substrates. In addition, thick InGaN layers (∼200-300nm) were successfully grown on Al2O3/ZnO and bare ZnO substrates. These results are significant as previous studies showed decomposition of the layer at InGaN thicknesses of 100nm or less.

In this manuscript, we study the magnetic property of Al-doped/Al2O3-doped ZnO films. We found that metallic Al-doped ZnO film shows room temperature ferromagnetism (RTFM). RTFM is correlated with the interaction of Al metallic clusters and ZnO matrix. The charge transfer has been observed between metallic Al and ZnO matrix. Therefore, RTFM in metallic Al doped ZnO may be highly probable due to charge transfer between metallic Al clusters and ZnO matrix. For Al2O3-doped ZnO film (denoted as (Zn1-x, Alx)O), RTFM was found in (Zn1-x, Alx)O film with a certain Al concentration range (16 mol%<x<50 mol%). The saturation magnetization is maximized in (Zn0.70, Al0.30)O film. The mechanism of RTFM can be explained as the interaction of ZnO nanocrystals (NCs) embedded in the amorphous phase and defects surrounding them.