TiO2 inverse opals by atomic layer deposition for solar cell

Abstract

In a large variety of industries, fabrication of uniform high Aspect Ratio (AR) nanostructures is generating increasing interest due to its prospects. Therefore, many methods for the fabrication of high AR nanostructures have been proposed and attempted but none of which is able to approach the conformity achieved by the use of Atomic Layer Deposition (ALD). In this report, TiO2 inverse opals are fabricated using Polystyrene (PS) template and deposition kinetics was studied to ensure uniformity throughout the structure, as uniformity is important for its structural integrity and its functional properties. The deposition technique used for the inverse opal fabrication and the study of deposition kinetics would be ALD. PS opal templates are used and are infiltrated using 99.999% pure TiCl4 and deionised water. Based on the photonic properties shown by the TiO2 infiltrated opals, conventional pulse/purge ALD is compared to a self-made Close Vacuum Atomic Layer Deposition (CVALD). Results have shown that CVALD has better filling fractions up to higher aspect ratios, as CVALD allows higher deposition pressures and also has better control of filling pressures.