Chemical evolution, heteroepitaxy, and monolayer patterning of solution-derived lithium niobate thin layers

Integrated lithium niobate (LiNbO$\sb3$) thin films are of technical interest for frequency doubling and a variety of efficient photonic circuit element applications. Solution deposition of such films on near lattice-matched substrates has been conducted, allowing low temperature processing, stoichiometry control, doping capability, and waveguiding analysis of heteroepitaxial thin layers. The structural evolution, optical properties, and device patterning of such films are reported in this thesis.Films deposited on lattice matched substrates were crystallized at low temperatures ($<$700$\sp\circ$C) to form chemically pure, heteroepitaxial thin films of LiNbO$\sb3$. Atomic force microscopy and transmission electron microscopy of the films indicate the structure consists of highly oriented grains with mosaic rotational variance at the substrate interface to accomodate slight lattice mismatch. Optical properties including second harmonic generation, transmission spectra, fluorescence spectra, and waveguide attenuation losses have been characterized. In addition, films were doped with erbium and absorption and fluorescence spectra were compared to those of top-seeded solution grown single crystals.For use of such films as devices, the ability to pattern waveguides and other structures is desired. A novel oxide thin film selective deposition method involving modification of substrate surfaces with patterns of hydrophobic monolayers has been developed. Ambient, selective deposition of (00.1) oriented LiNbO$\sb3$ heteroepitaxial strip waveguides with lateral dimensions as small as 4$\mu$m has been demonstrated. Application of this technique for integrated, high K$\sp\prime$ dielectric thin film patterning is also reported. The method enables low-temperature selective deposition of oxide thin film devices without the need for lithography or post-deposition etching processes.U of I OnlyETDs are only available to UIUC Users without author permissio