Structural and Electronic Response of Multigap N-Doped In₂Se₃: A Prototypical Material for Broad Spectral Optical Devices

The production of controlled doping in two-dimensional semiconductor materials is a challenging issue when introducing these systems into current and future technology. In some compounds, the coexistence of distinct crystallographic phases for a fixed composition introduces an additional degree of complexity for synthesis, chemical stability, and potential applications. In this work, we demonstrate that a multiphase In₂Se₃ layered semiconductor system, synthesized with three distinct structures─rhombohedral α and β-In₂Se₃ and trigonal δ-In₂Se₃─exhibits chemical stability and well-behaved n-type doping. Scanning tunneling spectroscopy measurements reveal variations in the local electronic density of states among the In₂Se₃ structures, resulting in a compound system with electronic bandgaps that range from infrared to visible light. These characteristics make the layered In₂Se₃ system a promising candidate for multigap or broad spectral optical devices, such as detectors and solar cells. The ability to tune the electronic properties of In₂Se₃ through structural phase manipulation makes it ideal for integration into flexible electronics and the development of heterostructures with other materials.