Detecting a Hierarchy of Deep-Level Defects in the Model Semiconductor ZnSiN2

Recent developments in the materials synthesis of the Zn-IV-N-2 system, including the alloy-free band gap tuning and synthesis of freestanding single crystals, reveal a system with potentially very broad applications. For that, important basic properties of these materials, such as the electronic band gap and the characteristics of defects, must be well understood, which has therefore become an urgent problem. In this work, X-ray absorption spectroscopy, X-ray emission spectroscopy, and density functional theory are utilized to characterize ZnSiN2. Excellent agreement between theory and experiment is obtained, with the band gap of ZnSiN2 determined to be 4.7 +/- 0.3 eV. X-ray-excited optical luminescence spectroscopy is used to determine the presence of two deep-level defects, which are identified as due to the presence of nitrogen vacancies.