Direct Observation of the Layer-by-Layer Growth of ZnO Nanopillar by In situ High Resolution Transmission Electron Microscopy

Abstract

Catalyst-free methods are important for the fabrication of pure nanowires (NWs). However, the growth mechanism remains elusive due to the lack of crucial information on the growth dynamics at atomic level. Here, the noncatalytic growth process of ZnO NWs is studied through in situ high resolution transmission electron microscopy. We observe the layer-by-layer growth of ZnO nanopillars along the polar [0001] direction under electron beam irradiation, while no growth is observed along the radial directions, indicating an anisotropic growth mechanism. The source atoms are mainly from the electron beam induced damage of the sample and the growth is assisted by subsequent absorption and then diffusion of atoms along the side surface to the top (0002) surface. The different binding energy on different ZnO surface is the main origin for the anisotropic growth. Additionally, the coalescence of ZnO nanocrystals related to the nucleation stage is uncovered to realize through the rotational motions and recrystallization. Our in situ results provide atomic-level detailed information about the dynamic growth and coalescence processes in the noncatalytic synthesis of ZnO NW and are helpful for understanding the vapor-solid mechanism of catalyst-free NW growth.

A Deep Learning Approach to Identify Local Structures in Atomic‐Resolution Transmission Electron Microscopy Images

“…This development has been accelerated by the advent of faster and more sensitive detectors such as the direct detection camera [1] ; but also by the development of the environmental TEM, where it becomes possible to study how, for example, nanoparticles respond to reaction gases in real time. Examples include characterizing the distribution of dopants [3] and defects, [4] in situ imaging of phase transformations, [5] structural reordering during materials growth, [6,7] dynamic surface phenomena, [8] and identification of chemical phases in nanoparticles. In many applications, accurate identification and classification of local DOI: 10.1002/adts.201800037 structure is a crucial first step in deriving useful information from atomic-resolution images.…”

“…In many applications, accurate identification and classification of local structure is a crucial first step in deriving useful information from atomic‐resolution images. Examples include characterizing the distribution of dopants and defects, in situ imaging of phase transformations, structural reordering during materials growth, dynamic surface phenomena, and identification of chemical phases in nanoparticles …”

Synthesis, Characterization, and Three-Dimensional Structure Generation of Zinc Oxide-Based Nanomedicine for Biomedical Applications

“…It can be used to visualize inorganic, organic, carbon-based, biological, and complex materials as spherical and equiaxial particles, tubes, flakes, rods, or fibers. The size, size distribution, crystalline structures, and aggregates of ZnO NPs have been analyzed using TEM [46,118,119]. The TEM technique is extensively used to determine the size, size distribution, and morphology of ZnO NPs based on the stabilizer (glycerol)-to-zinc source ratios during the synthesis [46,109].…”

“…The TEM technique is extensively used to determine the size, size distribution, and morphology of ZnO NPs based on the stabilizer (glycerol)-to-zinc source ratios during the synthesis [46,109]. Li et al [118] reported the layer-by-layer growth of ZnO nanopillar crystals using in situ, high-resolution TEM. Ludi and Niederberger [119] also used TEM to demonstrate the nucleation and growth of ZnO NPs, including the hexagonal pyramid and oleic acid-stabilized, cone-shaped ZnO nanocrystals in liquid media.…”

Highly Sensitive UV Photodiode Composed of β-Polyfluorene/YZnO Nanorod Organic-Inorganic Hybrid Heterostructure

“…For the last two decades, ZnO nanostructures have garnered substantial attention because of their prodigious potential for blue and ultra-violet (UV) optoelectronic devices [1][2][3][4][5][6]. Among various nanostructures, 1-dimensional ZnO (e.g., nanorod [7,8], nanoneedle [9,10], nanopillar [11,12], etc.) is one of the most attractive nanoarchitectures due to its short pathway for carrier transport [13], high surface-to-volume ratio for photon collection [14], and low exciton-phonon coupling strength [15].…”