Thickness dependent properties of quasi-layered MgGeN2 thin films

摘要

? 2023 Elsevier B.V.The electronic and optical properties are investigated for thin films of a newly discovered MgGeN2 Pnma phase. It was found that the properties show strong dependence on the thickness of the film. For multilayer in odd number, the band gap decreases from the 2.574 eV of trilayer down to 2.350 eV of pentalayer and then to 2.202 eV of heptalayer. For multilayer in even number, the band gap decreases from the 2.866 eV of bilayer down to 2.692 eV of quadlayer and then to 2.670 eV of hexalayer. The variation is coming from the number of surface layer and sub-surface layer as well as their bonding relations. Moreover, the various multilayers induced direct band gap in some cases, while indirect in others. Thus, the thickness control can be utilized for device design, and hence may widen the potential applications of II-IV-N2 ternary nitrides.