Preparation of ZnGeP2 for Nonlinear Optical Applications: Melt and Homoepitaxial Vapor Growth, Properties of the Grown Crystals

摘要

Nonlinear optical materials are needed for use in atmospheric monitoring and remote sensing applications. ZnGeP2 is one of the most highly efficient nonlinear optical media for the middle infrared. This paper describes a research program to grow ZnGeP2 crystals and to investigate the relationship of composition to crystal structure to optical properties. The latter (transparency and damage threshold) determines the use of the material in nonlinear optics. It is known that for ZnGeP2 structural perfection is mainly determined by defects formed due to deviations from stoichiometry during synthesis and growth. Postgrowth treatment improves the physical properties of the crystals. For this project, the ZnGeP2 crystals were produced using two different synthesis techniques (one- and two-temperature synthesis and seeded melt and vapor growth). A vapor growth technology using the chlorine method was created and applied to grow monocrystalline layers of ZnGeP2. Postgrowth treatments were carried out on these crystals. The grown and treated crystals were characterized by optical microscopy, scanning microscopy, transmission electron microscopy, microprobe analysis, and X-ray analysis. The authors were able to prepare high quality ZnGeP2 crystals, and they obtained new data on the optical properties of ZnGeP2. The results will have a great impact on the development of modern optical devices and systems and the control and management of industrial processes. Vapor growth experiments will provide data on the mechanisms of vapor growth for ZnGeP2, defect formation, and the nature of defects in film and volume ZnGeP2 crystals. The paper includes a bibliography of published papers (4) and reports (3) as well as conference presentations (10) with abstracts. (2 tables, 11 figures, 27 refs.).