Electronic structure and chemical bonding in transition-metal-mixed gallium oxide (Ga2O3) compounds

• Published in: The Journal of physics and chemistry of solids 2021-10, Vol.157, p.110174, Article 110174
• Main Authors: Ramana, C.V., Roy, Swadipta, Zade, Vishal, Battu, Anil K., Makeswaran, Nanthakishore, Shutthanandan, V.
• Format: Article
• Language: English
• Subjects: Doping; Electronic properties; Ga2O3 composites; β-Ga2O3
• ISSN: 0022-3697; 1879-2553
• DOI: 10.1016/j.jpcs.2021.110174

Transition metal (TM)-mixed gallium oxide (Ga2O3) ceramic compounds have potential applications in optical, optoelectronic, and photovoltaic devices. Herein, we report on the salient electronic structures and chemical properties of a series of such compounds, with a view to optimizing performance. The TM-mixed Ga2O3 (Ga2-xMxO3; TM-GO; 0.0 ≤ x ≤ 0.3, M = Fe, Ti, W) polycrystalline compounds were synthesized by a conventional, high-temperature solid-state reaction method. The effects of Fe-, Ti-, and W-doping on the electronic structures of the TM-GO compounds have been studied. The chemical states of Fe, Ti, and W ions in the TM-GO compounds vary as a function of TM concentration. The electronic structures and chemical states of the respective ions are greatly modified when Fe, Ti, or W ions are mixed in Ga2O3. For Fe and W, mixed chemical states (Fe2+/Fe3+, W4+/W6+) are evident in single-phase TM-GO compounds for lower x. On the contrary, Ti ions are invariably in their highest oxidation state (Ti4+) for all x in Ti-mixed-Ga2O3 compounds. Irrespective of the TM dopant, Ga ions exist in their highest oxidation state (Ga3+). The fundamental scientific understanding of the electronic properties, and tunability thereof, of TM-GO compounds presented in this detailed study should be useful when considering them for application in electronic, optoelectronic, or energy devices, or related technological fields. [Display omitted] •Tunable electronic properties are demonstrated in transition-metal-doped Ga2O3.•Ga2-xMxO3 (0.0 ≤ x ≤ 0.3, M = Fe, Ti, W) compounds have been synthesized by solid-state reaction.•The electronic structure is greatly modified when Fe, Ti, or W ions are doped in Ga2O3.•Fe and W exhibit mixed chemical states (Fe2+/Fe3+, W4+/W6+), whereas Ti is invariably present as Ti4+.•The electrochemical activity of doped Ga2O3 indicates its application potential in energy technologies.