Apex angle reduction in a LED device with a LED array
A Light Emitting Diode (LED) device, particularly a micro-LED (μLED) device, suitable for a μLED display is described. The LED device comprises a LED array with a plurality of LEDs 12 . It also comprises at least one top contact and bottom contact electrically connected to the LED array. Further, it comprises a conductive structure arranged above the LED array and the top contact, respectively, and electrically connected to the top contact. The conductive structure is, regarding each LED of the LED array, configured to absorb a first part of the light emitted by the LED, and to pass a second part of the light emitted by the LED. An emission angle (beam angle) of the passed light is thereby smaller than an emission angle of the light emitted by the LED.
1. A Light Emitting Diode, LED, device, comprising:
a LED array including a plurality of LEDs,
at least one top contact and bottom contact electrically connected to the LED array,
a conductive structure arranged above the LED array and the top contact, respectively, and electrically connected to the top contact, and
a plurality of lenses arranged between the LED array and the conductive structure,
wherein each lens is configured to focus at least some light emitted by one of the plurality of LEDs, so that the focused light is passed by the conductive structure,
wherein the conductive structure is, regarding each LED, configured to absorb a first part of the light emitted by the LED, and to pass a second part of the light emitted by the LED, and
wherein an emission angle of the passed light is smaller than an emission angle of the light emitted by the LED.
2. The LED device according to claim 1 , wherein the emission angle of the passed light is an angle of 60° or less.
3. The LED device according to claim 2 , wherein the emission angle of the passed light is an angle of 40-50°.
4. The LED device according to claim 1 , further comprising:
a plurality of lenses arranged above the conductive structure, wherein each lens is configured to focus the light that is emitted by one of the plurality of LEDs and is passed by the conductive structure.
5. The LED device according to claim 4 , wherein the top contact includes a transparent top contact connected to several or each of the plurality of LEDs and arranged between the LED array and the conductive structure.
6. The LED device according to claim 1 , wherein the top contact includes a transparent top contact connected to several or each of the plurality of LEDs and arranged between the LED array and the conductive structure.
7. The LED device according to claim 1 , wherein the conductive structure comprises a light-absorbing layer to absorb light emitted by the plurality of LEDs, and optionally,
wherein the light-absorbing layer includes a carbon layer or a layer of a high refractive index material.
8. The LED device according to claim 7 , wherein the top contact includes a transparent top contact connected to several or each of the plurality of LEDs and arranged between the LED array and the conductive structure.
9. The LED device according to claim 8 , wherein the conductive structure is connected to regions of a top surface of the top contact, the regions being positioned above spaces between adjacent LEDs.
10. The LED device according to claim 1 , wherein the conductive structure comprises a plurality of transparent openings, each transparent opening being related to one of the plurality of LEDs.
11. The LED device according to claim 10 , wherein the conductive structure comprises a plurality of vertical posts, the vertical posts being positioned above spaces between the plurality of LEDs and configured to separate adjacent LEDs from each other.
12. The LED device according to claim 10 , wherein an upper surface of the conductive structure defines the transparent openings and is located above the LED array.
13. The LED device according to claim 1 , wherein the LED array has a LED pixel pitch between 1-10 μm and/or a height of the conductive structure is between 0.1-1 times a LED pixel pitch of the LED array.
14. The LED device according to claim 13 , wherein the LED pixel pitch is equal to or below 3 μm and/or the height of the conductive structure is between 0.5-0.8 times the LED pixel pitch of the LED array.
15. The LED device according to claim 1 , wherein the conductive structure comprises a metallic core, and optionally,
wherein the metallic core includes a copper core and is embedded in a dielectric material.
16. The LED device according to claim 1 , further comprising:
a plurality of bottom contacts, wherein each bottom contact is electrically connected to one of the plurality of LEDs, and
a Complementary Metal-Oxide-Semiconductor, CMOS, integrated circuit, IC, connected through the bottom contacts to the LEDs and configured to drive the LED array.
17. The LED device according to claim 1 ,
wherein the LED device is an integrated LED chip or wafer, and optionally,
wherein the LED array, the at least one top contact and bottom contact and the conductive structure are integrated.
18. A method for fabricating a Light Emitting Diode, LED, device, the method comprising:
processing a LED array including a plurality of LEDs,
processing at least one top contact and bottom contact electrically connected to the LED array,
processing, with a damascene process, a conductive structure arranged above the LED array and the top contact, respectively, and electrically connected to the top contact, and
processing a plurality of lenses arranged between the LED array and the conductive structure,
wherein each lens is configured to focus at least some light emitted by one of the plurality of LEDs, so that the focused light is passed by the conductive structure,
wherein the conductive structure is, regarding each LED, configured to absorb a first part of the light emitted by the LED, and to pass a second part of the light emitted by the LED, and
wherein an emission angle of the passed light is smaller than an emission angle of the light emitted by the LED.