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  Petersen, C.; Schultz, T.; Andreassen, M.; Vogt, S.; Koch, N.; Grundmann, M.; von Wenckstern, H.: Toward Ultrawide Bandgap Engineering: Physical Properties of an α-(Ti_xGa_1-x)₂O₃ Material Library. Physica Status Solidi - Rapid Research Letters early view (2025), p. 2500033/1-9

10.1002/pssr.202500033
Open Access Version (externer Anbieter)

Abstract:
Due to its high bandgap of 5.3–5.6 eV and high predicted breakdown field of 10 MV cm−1, much attention is drawn to the ultrawide bandgap semiconductor α-Ga2O3 for applications in high-power and solar blind optoelectronic devices. In contrast to the thermodynamically most stable β-phase of Ga2O3, various transition metal sesquioxides with rhombohedral crystal structure and similar lattice constants to α-Ga2O3 are available for bandgap engineering toward lower bandgap energies. Therefore the material system α-(TixGa1−x)2O3 in principle offers the possibility to tune the materials bandgap for wavelength selective optoelectronics over an extremely wide range from 5.6 eV (α-Ga2O3) down to 0.14 eV (α-Ti2O3). In this work, high-throughput combinatorial synthesis by pulsed laser deposition is employed to realize a spatially addressable material library covering almost the entire composition range within the ternary (TixGa1−x)yOz solid solution. Phase-pure growth of (TixGa1−x)2O3 up to x = 0.25 is reported, exceeding previously found miscibility limits by a factor of 5. The physical properties of the material system are investigated in relation to x and bandgap engineering within the rhombohedral α-(TixGa1−x)2O3 material system is demonstrated over an up to now unprecedented large spectral range from 4.4 to 5.3 eV.