Growth Mechanism of Preferred Crystallite Orientation in Transparent Conducting ZnO:In Thin Films

Abstract

Texture engineering of thin films with controlled crystalline orientation is essential in tuning their properties. We have successfully prepared ZnO:In thin films via chemical bath deposition (CBD), with the preferred orientation of the films varying from [002] to [100] and [110] by simply altering the solvent composition. Growth mechanism of the preferred crystallite orientation in ZnO:In thin films have been systematically investigated. It is found that the variation in the preferred orientation in the films obeys the principle of evolutionary selection, that is, the fastest-growing crystallographic direction determines the preferred orientation of the films. The tunable crystallite orientation indicates no epitaxial relationship has been established between the crystallites and the seeds. XPS analysis reveals the successful incorporation of indium in the ZnO:In thin films and the oxygen desorption upon reductive annealing. CBD, thus, is demonstrated to produce transparent conductive oxide thin films with tunable textures.

Investigations on the Crystallographic Orientation Induced Surface Morphology Evolution of ZnO Thin Films and Their Wettability and Conductivity

“…In general, ZnO columnar nanostructures with c -axis crystallographic orientation are most commonly obtained in several nanosynthesized methods including wet and physical–chemical vapor deposition techniques. A lot of models have been developed to explain crystal growth mechanism including preferential nucleation, sticking probability on each plane, surface diffusion of adatoms, and growth rate anisotropy of the different crystallographic planes. − Here, we deduce a growth mechanism to interpret the crystallographic orientation evolution of ZnO thin film depending on the synthesized temperature, which is on the basis of the DEZn as a precursor that could be decomposed into different chemical species such as metal zinc, ethyl groups, and its fragments under different synthesized temperatures and then further influence the nucleation and growth of grains . For verifying and better understanding this growth mechanism in our case, the in situ OES analysis was used to monitor plasma chemical composition during the synthesis process as shown in Figure , and Figure depicts a schematic drawing for the proposed growth mechanisms.…”

Oriented Nano–Microstructure‐Assisted Controllable Fabrication of Metal–Organic Framework Membranes on Nickel Foam

“…Due to the 1D pore structure of these MOFs, in order to get a desired membrane with highly effi cient molecule permeation property, their crystals should grow directionally to allow the pores run-through and be perpendicular to the substrate surface. [ 40,41 ] In order to further analyze the membrane growth orientation, orientation indices (OIs) were calculated for the three main diffractions. With the help of the nano-microstructure arrays the oriented growth of M 3 (HCOO) 6 crystals on the Ni foam indeed becomes feasible.…”

Increasing Polycrystalline Zinc Oxide Grain Size by Control of Film Preferential Orientation

“…Each particular application requires transparent conductive oxides (TCOs) with specific properties, such as a high carrier mobility, some of which can be tuned by changing the film microstructure. In order to tailor the film microstructure, a detailed knowledge of the mechanisms governing film growth is necessary. − Growth of films by chemical vapor deposition (CVD) techniques depends strongly on the chemical reactions happening at the film surface. − These reactions and hence film growth are influenced by controllable parameters such as substrate temperature and gas precursor flows. − On the basis of current growth models of low pressure metal–organic chemical vapor deposited (LPMOCVD) ZnO, , these parameters influence how adatoms form new nuclei on the substrate and determine adatom sticking coefficients on the different crystal facets or exposed grain faces, which leads to a growth-velocity anisotropy. Grains with their fastest growth direction perpendicular to the film substrate overgrow grains oriented otherwise and hence dominate the late-stage texture and morphology of the film .…”