Microstructure and optical properties of Al2O3 prepared by oblique deposition using microsphere shell templates.

We fabricated an orderly inclined Al2O3 column array using a hollow microsphere template. The microstructure and optical properties were investigated with scanning electron micrography and a UV/VIS spectrometer, respectively. Microsphere shell templates were formed using atomic layer deposition to prevent the melting of polystyrene microspheres during the following high-temperature deposition process. An inclined Al2O3 column array with a 30° tilt angle was grown by oblique deposition on a substrate with a 75.5° tilt angle with respect to the substrate normal. Birefringence and photonic crystalline behavior can be observed in the orderly inclined column array. The difference in the refractive indices between the p and s polarizations of the orderly inclined Al2O3 column array was about 0.1. The photonic properties of the crystal were enhanced compared to those of substrates without patterns.