This work reports on the controlled growth of well-aligned ZnO micro/nanorod arrays at low temperature on GaN
substrates. The influence of GaN surface morphology and doping on the growth of ZnO rods via hydrothermal method
is studied. The structural properties of ZnO rods are investigated using field-emission scanning electron microscopy
(FESEM) and X-ray diffraction (XRD). The grown ZnO rods show preferred orientation along the c-axis and are well
aligned with high aspect ratios. For precisely controlling the formation of well-aligned ZnO micro/nanorod arrays, a
two-dimensional periodic polymer aperture arrays on top of GaN is also utilized for selective growth of ZnO rods. The
size of ZnO rods is controlled over a considerably wide size range from 130 nm up to 3.5 μm in diameter by tuning the
aperture size of the pattern and solution concentrations. It is observed that the ZnO rods are not grown directly through
the aperture template. In addition, the size of ZnO rods is found to be dependent on the geometry of polymer aperture
arrays. The detailed growth behavior is characterized and analyzed. This work provides a route to achieve the
low-temperature heteroepitaxy of ZnO mirco/nanorod arrays on GaN, which can be very useful for many
optoelectronics applications, especially for light emitting diodes.
Sol-gel preparation of amorphous titanium oxide (TiO<sub>x</sub>) thin films with distinct morphological properties on the
hydrophobic substrate was obtained by solution spin coating method. The TiO<sub>x</sub> thin films were deposited by three
precursors using 2-methoxyethanol (2MOE), isopropanol (IPA) and mixture of 2MOE and hexane as solvents. We
demonstrate evidence that the morphology of TiO<sub>x</sub> thin film is strongly related to the employment of dissimilar solvent.
Among these three solvents, TiO<sub>x</sub> film obtained from 2MOE/hexane mixed solvent is a superior choice for the
preparation of TiO<sub>x</sub> thin film on the hydrophobic substrate because of its smooth surface morphology.
We demonstrate the method of transferring aligned single crystal silicon nanowires (SiNWs) to transparent
substrate. The alignment of the transferred nanowires is almost identical to the original one. The density of the
transferred SiNWs can achieve 3×10<sup>7</sup> nanowires/mm<sup>2</sup>. The low temperature fabrication processes are compatible for a wide range of substrates. The transmission coefficient below 10 % at a wide bandwidth, 400-1100 nm, was found in the transferred SiNWs. The high dense aligned SiNWs are promising for future photovoltaic applications.
The fabrication of metallic photonic boxes and their emission properties with black-body radiation at high temperatures are reported. Black-body radiation is modified to enhance the visible spectrum using photonic boxes of about 200 nm. With the structure of resonant cavity and the significantly enhanced density of states at specific wavelengths, the enhanced blue light is observed and it has the peak intensity at 400 nm with 90nm spectral width. Other visible spectra can also be enhanced by simply increasing the size of photonic boxes. Due to the high temperature operation, formation of metallic grain on the surface of photonic boxes is also discussed.