Nature of microcracks in photonic-crystal opal films grown by the moving-meniscus method

Abstract

In all studies devoted to the growth of photoniccrystal (PC) opal films by the moving-meniscus method [1‐7], one notices the presence of microcracks, which lead to shorts when the PC films are used in conducting nanocompositions. Among various defects inherent in opal nanocrystals, such as the shifts of layers and rows of monodisperse spherical silica particles (MSSPs), point defects (MSSP vacancies, stacking faults, etc.) [8] and microcracks (reaching several tens of MSSP diameters in length) are the most serious defects. The appearance of other defects can be avoided to a considerable extent by using high-quality MSSP suspensions with a highly monodisperse character of particle size distribution and by growing PC films under conditions close to equilibrium, whereas microcracks are naturally inherent in the obtained material. To the best of the authors' knowledge, the reasons and mechanisms responsible for microcrack propagation during the growth of single-crystal PC opal films have not been considered in the available literature. In this study, we present the first analysis of these issues.