Phosphor separated from LED by transparent spacer

摘要

To reduce absorption by an LED die (12) of light emitted by a phosphor layer (48), the absorbing semiconductor layers of the LED die (12) are separated from the phosphor layer by a relatively thick glass plate (44) affixed to the LED die or by the LED die transparent growth substrate. Therefore, phosphor light emitted at a sufficient angle towards the LED die will pass through the transparent spacer (44) and exit the sidewalls of the spacer, preventing the light from being absorbed by the LED die. The LED die may be GaN based. The spacer is at least 100 microns thick. A 16% gain in light extraction is achievable using the technique compared to the light emission where phosphor is directly deposited on the LED semiconductor layers.

主权项

1. A phosphor-converted light emitting diode (LED) structure comprising:
an LED die having epitaxial semiconductor layers grown on a growth substrate, wherein the growth substrate has been removed; a substantially transparent layer affixed to a top surface of the LED die, the substantially transparent layer having a thickness greater than 250 microns, the substantially transparent layer having a top surface and sidewalls; and a phosphor layer in direct contact with the top surface and sidewalls of the substantially transparent layer such that some light emitted by the phosphor layer into the substantially transparent layer exits out of the sidewalls of the substantially transparent layer.