Ceramic-based thin-film blue LEDs with high operation voltage and unsaturated output power at 1800W/cm²

III-nitride blue (λ = 450 nm) LEDs were fabricated on ceramic substrates using thin-film and high-voltage processes. The device, comprising sixteen cascaded sub-LEDs, exhibits excellent current spreading and thermal resilience. Under the driving power of 1800W/cm² (J = 450 A/cm ²), the high-voltage thin-film LED delivers unsaturated output power and alleviated efficiency droop, which is not achievable with devices fabricated on Si or sapphire substrates with identical epitaxial structure.