Optical properties of epitaxial ZnGeAs$_{2}$ thin film

Chalcopyrite ZnGeAs$_{2}$ lattice-matched to GaAs(001) is a promising 1.1 eV band gap semiconductor for applications in nonlinear photonic devices and multijunction solar cells. Knowledge of the optical functions of a material over a wide photon energy range is of importance to optimize photonic and photovoltaic device structures. We present room-temperature optical properties of a ZnGeAs$_{2}$ thin film grown epitaxially on a GaAs(001) substrate by metalorganic vapor phase epitaxy. Spectroscopic ellipsometry was employed to measure the pseudodielectric function of the ZnGeAs$_{2}$ thin film, and was compared with a theoretical calculation within the quasiparticle self-consistent GW approximation. The interband-transition critical-point energies were obtained from a standard lineshape analysis of the measured spectrum. We will also present a comparison of the optical properties of ZnGeAs$_{2}$ with those of other II-IV-V$_{2}$ chalcopyrite compounds as well as their corresponding III-V zincblende compounds. This abstract is subject to government rights.