Structural and electrical properties of c-plane α-Ga2O3 grown by halide vapor phase epitaxy on a nearly lattice-matched high-quality α-(Cr0.8Fe0.2)2O3/sapphire template
Year: 2026
Type: article
Abstract: Epitaxial growth of α-Ga2O3 using high-quality c-plane α-Cr2O3/sapphire templates with a small in-plane lattice mismatch (Δa/a = −0.45%) has attracted considerable attention in recent years. However, achieving a low dislocation density on the order of 107 cm−2, comparable to that of the α-Cr2O3 layer, requires limiting the epilayer thickness to the submicron range. In this study, α-Ga2O3 films with thicknesses of 2.4–21 μm were grown by halide vapor phase epitaxy on high-quality c-plane α-(Cr0.8Fe0.2)2O3/sapphire templates, which exhibit a smaller in-plane lattice mismatch of −0.14%. X-ray 2θ–ω scans and pole figure measurements confirmed phase-pure single-crystalline α-Ga2O3. Reciprocal space mapping revealed that the α-Ga2O3 diffraction peak remained at the fully strained position beyond the theoretical critical thickness of 5.2 μm, although slight tail broadening suggested the onset of relaxation. Neither the crystal orientation fluctuation estimated from X-ray rocking curves nor the dislocation density determined by etch pit counting increased with film thickness. The dislocation density remained below 2 × 107 cm−2 for all films. Transmission electron microscopy revealed slightly inclined mixed-type dislocations. Si-doped thick α-Ga2O3 films exhibited a room-temperature Hall mobility (μ) that increased monotonically with decreasing carrier concentration (n), reaching μ = 203 cm2V−1s−1 at n = 2.2 × 1016 cm−3, the highest value reported for α-Ga2O3 and comparable to the best values reported for β-Ga2O3. Low-temperature Hall-effect measurements further revealed a Si donor ionization energy of 33.0 ± 0.5 meV and an exceptionally high μ of 3.0 × 103 cm2V–1s–1 at 46.3 K. These results demonstrate a practical route to growing high-quality thick α-Ga2O3 epilayers with superior electrical properties, paving the way for high-performance α-Ga2O3 power devices. High-quality α-Ga2O3 thick filmswith low dislocation densities were realized using α-(Cr0.8Fe0.2)2O3 templates, enabling the highest reported α-Ga2O3 mobility, comparable to the best β-Ga2O3 values.
Source: Figshare
Language: English
Topic: Ga2O3 and related materials
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7225820253
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