US 12,224,375 B2
Light emitting diode with improved colour purity
Jun-Youn Kim, Plymouth (GB); Samir Mezouari, Plymouth (GB); John A. Shannon, Plymouth (GB); Kevin Stribley, Plymouth (GB); and Mohsin Aziz, Plymouth (GB)
Assigned to Plessey Semiconductors Limited, Plymouth (GB)
Appl. No. 17/631,027
Filed by PLESSEY SEMICONDUCTORS LIMITED, Plymouth (GB)
PCT Filed Jul. 24, 2020, PCT No. PCT/EP2020/071005
§ 371(c)(1), (2) Date Jan. 28, 2022,
PCT Pub. No. WO2021/018784, PCT Pub. Date Feb. 4, 2021.
Claims priority of application No. 1911008 (GB), filed on Aug. 1, 2019.
Prior Publication US 2022/0271193 A1, Aug. 25, 2022
Int. Cl. H01L 33/06 (2010.01); H01L 33/10 (2010.01); H01L 33/46 (2010.01); H01L 33/52 (2010.01); H01L 33/58 (2010.01)
CPC H01L 33/06 (2013.01) [H01L 33/10 (2013.01); H01L 33/46 (2013.01); H01L 33/52 (2013.01); H01L 33/58 (2013.01)] 25 Claims
OG exemplary drawing
 
1. A light emitting diode comprising:
a LED layer configured to emit pump light having a pump light wavelength from a light emitting surface, the LED layer comprising a plurality of Group III-nitride layers;
a container layer provided on the light emitting surface of the LED layer, the container layer having a container surface on an opposite side of the container layer to the light emitting surface, the container surface including an opening defining a container volume through the container layer to the light emitting surface of the LED layer;
a colour converting layer provided in the container volume, the colour converting layer configured to absorb pump light and emit converted light of a converted light wavelength longer than the pump light wavelength; and
a lens provided on the container surface over the opening, the lens having a convex surface on an opposite side of the lens to the colour converting layer;
a pump light reflector laminate provided over the convex surface of the lens, the pump light reflector laminate having a stop-band configured to reflect the pump light centred on a first wavelength comprising:
a first interface layer provided on the convex surface of the lens; the first interface layer having a first thickness and a first refractive index, wherein a product of the first refractive index and first thickness is one eighth of the first wavelength;
a plurality of layers alternating between:
a low reflectance layer having a second refractive index and a second thickness, wherein the second refractive index is lower than the first refractive index; and
a high reflectance layer having a third thickness and a third refractive index which is higher than the second refractive index,
wherein a product of the second refractive index and the second thickness for each of the low reflectance layers is one quarter of the first wavelength, and a product of the third refractive index and the third thickness for each of the high reflectance layers is one quarter of the first wavelength;
a second interface layer provided on a low reflectance layer of the plurality of layers, the second interface layer having a fourth refractive index and a fourth thickness,
wherein a product of the fourth refractive index and the fourth thickness is one eighth of the first wavelength, and the fourth refractive index is larger than the second refractive index,
wherein the opening at the container surface has a first characteristic diameter (Do) and the lens has a second characteristic diameter (D1) on the container surface, wherein the first and second characteristic diameters satisfy the relationship: 0.1 D1≤D0≤0.8 D1.