Simple fabrication process for 2D ZnO nanowalls and their potential application as a methane sensor.

Two-dimensional (2D) ZnO nanowalls were prepared on a glass substrate by a low-temperature thermal evaporation method, in which the fabrication process did not use a metal catalyst or the pre-deposition of a ZnO seed layer on the substrate. The nanowalls were characterized for their surface morphology, and the structural and optical properties were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and photoluminescence (PL). The fabricated ZnO nanowalls have many advantages, such as low growth temperature and good crystal quality, while being fast, low cost, and easy to fabricate.

Deep and alignment free patterned etching of GaN surface using an atomic force microscope.

Successful deep and alignment-free patterned etching on GaN using atomic force microscope (AFM) local oxidation followed by in-situ chemical etching is demonstrated. Oxide ridges are grown on GaN on an AFM by applying positive sample bias at 80% humidity, with the oxidation reaction expedited by UV light. The oxide ridges are then etched by HCl solution, leaving troughs in the GaN surface.

Direct patterning of zinc oxide with control of reflected color through nano-oxidation using an atomic force microscope.

Atomic force microscope oxidation on Zn creating amorphous ZnO (a-ZnO) with the a-ZnO showing multiple colors under white light at different oxidation voltages was successfully demonstrated. Simulation of reflected colors at different thicknesses of a-ZnO was also conducted. The presented technique can not only be applied to near diffraction limit multilevel optical data storage, but also makes it possible to represent the color spectra observed in nature at near diffraction limits.