This paper describes the application of organometallic vapor phase epitaxy to the growth of II-1V-V2 chalcopyrite materials that have high figures of merit for nonlinear optical (NLO) applications. ZnGeAs2, although not a particularly interesting NLO material, is used as a model for the growth of ZnGeP2, which is. Both compounds, as well as others, have been successfully grown by vapor phase on III-V substrates that provide a close lattice match. Doping studies using Group II and VI elements have been undertaken to control the p-type conductivity found in both compounds. Except for the possible case of indium, the results of these experiments are less than encouraging. Minority-carrier lifetimes of 150 ns have been measured in ZnGeAs2.
The results of this work are used to make projections about the growth of CdGeAs2. CdGeAs2 is promising for the next generation of NLO mid-infrared materials if an absorption band that occurs at about 5 μm can be reduced. The growth projections suggest that this compound will be difficult to grow epitaxially and has no III-V substrate that provides a close lattice match. Mixing CdGeAs2 with other II-IV-V2 materials may offer solutions to the substrate problem. The defect properties of CdGeAs2 have not, to our knowledge, been studied.