Computational and experimental studies on band alignment of ZnO/InxGa2−xO3/GaN heterojunctions

• Published in: The Journal of chemical physics 2023-04, Vol.158 (13), p.134720-134720
• Main Authors: Liu, Xilai, Zhao, Chunxiang, Niu, Chunyao, Jia, Yu
• Format: Article
• Language: English
• Subjects: Alignment; Amorphization; Atomic layer epitaxy; Atomic properties; Conduction bands; Doping; First principles; Gallium nitrides; Heterojunctions; Hybrid structures; Light emitting diodes; Offsets; Optical properties; Phosphors; Valence band; White light; Zinc oxide
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/5.0134277

The ZnO/GaN heterojunctions are extensively investigated now, owing to their good luminescent properties and devisable capability to form efficient hybrid structures. An electron-blocking layer inserted into heterojunctions can greatly change their properties. In this work, n-ZnO/β-InxGa2−xO3/p-GaN heterojunctions have been successfully formed using atomic layer deposition methods. We show that the doping of In can effectively tune the band edges of the heterojunctions. First-principle calculations reveal that the bandgap of bulk β-InxGa2−xO3 shrinks linearly with the increase in In contents, accompanied by an upward movement of the valence band maximum and a downward movement of the conduction band minimum. As the indium concentrations increase, the valence band offsets show an upward movement at both the InxGa2−xO3/GaN and ZnO/InxGa2−xO3 interfaces, while the conduction band offsets present different trends. A broad, reddish yellow-green emission appears after In doping, which verifies the effect of band alignment. What is more, we show that the amorphization of InxGa2−xO3 can play an important role in tuning the band edge. This work provides access to a series of band offsets tunable heterojunctions and can be used for the further design of direct white light-emitting diodes without any phosphors, based on this structure.