High electron mobility single-crystalline ZnSnN2 on ZnO (0001) substrates

Making a systematic effort, we have developed a single-crystalline ZnSnN2 on ZnO (0001) by reactive magnetron co-sputtering. Epitaxial growth was achieved at 350 C by co-sputtering from metal targets in nitrogen atmosphere, and confirmed by transmission electron microscopy (TEM) measurements. TEM verified that the layers are single-crystalline of hexagonal phase, exhibiting epitaxial relationship with the substrate. The screw-type threading dislocations originating from the interface were identified as dominant extended defects. More specifically, we report a pioneering measurement of the dislocation density in this material. Even though, there is no literature data for direct comparison, such values are typical of heteroepitaxial growth of III-nitride layers without applying defect density reduction strategies. The films demonstrated a record electron mobility. The optical bandgaps of 1.86 eV and 1.72 eV were determined for the stoichiometric and Zn-rich samples, respectively. As such, we conclude that ZnSnN2 is an earth-abundant, environmentally-friendly semiconductor and is a promising candidate for cost efficient components in electronics and photonics.