LED USING LUMINESCENT SAPPHIRE AS DOWN-CONVERTER

摘要

An LED die includes a luminescent sapphire layer affixed to LED semiconductor layers. The luminescent sapphire absorbs a portion of the primary light and down-converts the primary light to emit secondary light. A phosphor layer may be added. The luminescent sapphire may comprise luminescent sapphire particles in a binder forming a mixture deposited over the LED semiconductor layers. Alternatively, the luminescent sapphire comprises a pre-formed tile that is affixed over the LED semiconductor layers. Alternatively, the luminescent sapphire comprises a luminescent sapphire growth substrate on which is epitaxially grown the LED semiconductor layers. After the LED die is formed, the luminescent characteristics of the sapphire maybe adjusted using optical conditioning and/or annealing to tune the die's overall emission.