Paper TF-WeM10
Effect of Atomic Layer Deposition Grown VO2 Film Morphology and Crystallinity on Opto-Electronic Phase Transition.

Wednesday, December 5, 2018, 11:00 am, Room Naupaka Salons 4

VO₂ is a promising material for a variety of opto-electronic applications due to its metal-to-insulator phase transition occurring near room temperature. Atomic layer deposition (ALD) is an advantageous technique to deposit VO₂ due to its excellent conformality and ability to deposit thin films at low temperatures allowing for growth on a variety of substrates and device architectures. Such conformality is especially useful for complex optical devices with non-planar structures such as waveguides or diffraction gratings. There is, however, no current ALD method for direct growth of crystalline VO₂, therefore post deposition annealing is required to achieve crystallinity. In this study, we examine the impact of annealing conditions on the resulting phase, crystallinity, composition, morphology, and metal-to-insulator transition of as-grown amorphous ALD VO₂ films on sapphire. By controlling annealing conditions such as temperature, time, and O₂ pressure, this study demonstrates a control over film morphologies and phase transition properties of the VO₂ film. One such example is decreasing the VO₂ film roughness by an order of magnitude by changing the annealing temperature by 100 °C, which simultaneously improves the hysteresis of the metal-to-insulator film transition. Through these efforts, the structure-property relationship of VO₂ will be revealed, which can then provide a guide for tailoring of optimal film properties for specific electronic and optical applications.