Macro- and micro-structural manifestation and engineering of large-size polycrystalline ZnSe

Abstract

Polycrystalline ZnSe is essential for broadband windows, lenses, and even nonlinear media because its intrinsic transmission covers from visible to mid- and far-infrared regions, and its nonlinear coefficient is larger than that of traditional materials. Its macro- and micro-structures determine its performance and further applications. This study investigates the macro- and micro-structural engineering of large-scale polycrystalline ZnSe, including the structure, morphology, defects and optical properties. The chemical vapor deposition method is used to prepare standard and multispectral ZnSe with sizes of up to 100 mm. As a supplement to a past study, different micro-defects and macro-island-like and coarse columnar structures are observed, and their formation mechanisms are determined. In addition, the influence of micro- and macro-structures on the spectra of the prepared materials is discussed and experimentally identified. More importantly, micro- and macro-structural engineering is used to optimize the preparation technology, thereby increasing the transmission of polycrystalline ZnSe to 75% with the optical bandgap of 2.54 eV, presenting an enhanced transparency compared with the commercialized ZnSe materials (71%). This study should be helpful for understanding the formation mechanism of macro- and micro-structures in polycrystalline materials and for optimizing the preparation technology of optical polycrystalline materials.