Uncovering cation disorder in ternary Zn1+xGe1-x(N1-xOx)2 and its effect on the optoelectronic properties

Ternary nitride materials, such as ZnGeN2, have been considered as hopeful optoelectronic materials with an emphasis on sustainability. Their nature as ternary materials has been ground to speculation of cation order/disorder as a mechanism to tune their bandgap. We herein studied the model system Zn1+xGe1-x(N1-xOx)(2) including oxygen - which is often a contaminant in nitride materials - using a combination of X-ray and neutron diffraction combined with elemental analyses to provide direct experimental evidence for the existence of cation swapping in this class of materials. In addition, we combine our results with UV-VIS spectroscopy to highlight the influence of disorder on the optical bandgap.