Crystal Perfection of Particle Monolayer at the Air-Water Interface

Crystal growth in colloidal particle monolayers fabricated by Langmuir-Blodgett method on 4 in. sapphire wafers was investigated under the condition of two techniques, that is, ultrasonic annealing at 1.2 to 1.5 MHz and barrier-sway process at 0.2 to 0.5 Hz. Significant increases of the ordered area were obtained by the both techniques and more than 60 times growth was confirmed. The remaining crystal defects after the growth were categorized as grain boundary, vacancy, and line defect. Both techniques exhibited different features regarding the component ratio of the defects, and different mechanisms for the reorientation of particles are discussed. The driving force of these reorientations is thought to be associated with the 2D Ostwald ripening of colloidal crystals.