Characterization of the heteroepitaxial growth of 3C-SiC on Si during low pressure chemical vapor deposition

Abstract

3C-SiC heteroepitaxial layers were grown on Si substrates using a horizontal, hot-wall low pressure chemical vapor deposition system. The crystal quality, surface morphology and thickness uniformity of the layers were characterized by X-ray diffraction, atomic force microcopy and Fourier transform infrared spectroscopy, respectively. Growth of the epitaxial layer was determined to follow a three-dimensional island mode initially and then switch to a step-flow mode as the growth time increases. Barrier epithelia, especially airway epithelial cells, are persistently exposed to micro-organisms and environmental factors. To protect the host from these microbial challenges, many immune strategies have evolved. The airway epithelium participates in the critical innate immune response through the secretion of immune effectors such as mucin, antimicrobial peptides (AMP), and reactive oxygen species (ROS) to entrap or kill invading microbes. In addition, airway epithelial cells can act as mediators connecting innate and adaptive immunity by producing various cytokines and chemokines. Here, we present an overview of the role of mucosal immunity in airway epithelium, emphasizing the framework of bacterial and viral infections along with regulatory mechanisms of immune effectors in human cells and selected animal models. We also describe pathophysiological roles for immune effectors in human airway disease.