Heteroepitaxial growth of Eu-doped Ga 2 O 3 films on flexible substrates

Flexible luminescent oxides require mechanically compliant substrates that also provide crystalline templates for ordered film growth. Eu-doped Ga 2 O 3 films were deposited on flexible MgO(100)/amorphous Al 2 O 3 -buffered Hastelloy by oxygen-plasma-assisted pulsed laser deposition. Growth at 500 °C under 300 W plasma produced the most ordered film, exhibiting a β -Ga 2 O 3 (400) reflection, a rocking-curve full width at half maximum of 9.3°, and fourfold in-plane ordering with rotational domains. This film also showed the strongest Eu 3+ red emission, dominated by the 5 D 0 → 7 F 2 transition at 613–614 nm. Under outward bending, the characteristic emission profile was retained, while the integrated 5 D 0 → 7 F 2 intensity increased by up to 82.3% at a nominal strain of approximately 0.42%. The Raman mode near 201 cm −1 redshifted to 196.7 cm −1 at 6 mm and recovered to 200.0 cm −1 after release. After 10 3 bending cycles, the integrated emission retained 99.6% of its initial value, demonstrating strain-tunable luminescence and cyclic-bending stability.