Flip chip micro light emitting diodes
A micro-light emitting diode (uLED) device comprises: a mesa comprising: a plurality of semiconductor layers including an n-type layer, an active layer, and a p-type layer; a p-contact layer contacting the p-type layer; a cathode contacting the first sidewall of the n-type layer; a first region of dielectric material that insulates the p-contact layer, the active layer, and a first sidewall of the p-type layer from the cathode; an anode contacting the top surface of the p-contact layer; and a second region of dielectric material that insulates the active layer, a second sidewall of the p-type layer, and the second sidewall of the n-type layer from the anode. The top surface of the p-contact layer has a different planar orientation compared to the first and second sidewalls of the n-type layer. Methods of making and using the uLED devices are also provided.
1. A micro-light emitting diode (uLED) comprising:
a mesa comprising:
a plurality of semiconductor layers including an n-type layer, an active layer, and a p-type layer;
a p-contact layer contacting the p-type layer;
the mesa comprising a height spanning from a top surface of the p-contact layer to a bottom surface of the n-type layer and a width spanning a first sidewall of the n-type layer to a second sidewall of the n-type layer; the top surface of the p-contact layer having a different planar orientation compared to the first and second sidewalls of the n-type layer;
a cathode contacting the first sidewall of the n-type layer;
a first region of dielectric material that insulates the p-contact layer, the active layer, and a first sidewall of the p-type layer from the cathode;
an anode contacting the top surface of the p-contact layer; and
a second region of dielectric material that insulates the active layer, a second sidewall of the p-type layer, and the second sidewall of the n-type layer from the anode;
the cathode and the anode longitudinally spanning the uLED.
2. The uLED of claim 1 , wherein the width of the mesa is less than 100 micrometers.
3. The uLED of claim 1 , wherein the height of the mesa is less than or equal to the width of the mesa.
4. The uLED of claim 1 , wherein the longitudinal spanning of the uLED includes spanning the height of the mesa.
5. The uLED of claim 1 , wherein the p-contact layer contacting the p-type layer substantially spans a width of the p-type layer.
6. The uLED of claim 1 , wherein the cathode wraps around a portion of the n-type layer and a first portion of the first region of the dielectric material.
7. The uLED of claim 1 , wherein the anode wraps around portions of the p-contact layer and the second region of the dielectric material.
8. The uLED of claim 1 , wherein a first longitudinal surface of the cathode defines a first bonding surface of the uLED and a first longitudinal surface of the anode defines a second bonding surface of the uLED, the first longitudinal surface of the cathode and the first longitudinal surface of the anode being located on a same side of the p-contact layer.
9. The uLED of claim 8 , wherein the first longitudinal surface of the cathode and the first longitudinal surface of the anode are planar.
10. The uLED of claim 1 , wherein a second longitudinal surface of the cathode defines a first liftoff edge of the uLED and a second longitudinal surface of the anode defines a second liftoff edge of the uLED, the second longitudinal surface of the cathode and the second longitudinal surface of the anode being located on opposite sides of the n-type layer.
11. The uLED of claim 1 comprising a passivation layer located on the cathode, the anode, and a second portion of the first region of dielectric material.
12. The uLED of claim 1 , wherein the cathode contacts two planar orientations of the n-type layer.
13. The uLED of claim 1 , wherein the anode contacts two planar orientations of the p-contact layer.
14. The uLED of claim 1 , wherein the semiconductor layers have a total thickness in a range of from 2 μm to 10 μm.
15. The uLED of claim 1 , wherein the n-type layer comprises N-GaN and the p-type layer comprises P-GaN.
16. The uLED of claim 1 , wherein the dielectric material of the first region and of the second region independently each comprise a material selected from the group consisting of SiO 2 , AlO x , and SiN, each independently has a thickness in a range of from 200 nm to 1 μm.
17. The uLED of claim 1 , wherein a portion of the cathode is positioned above the top surface of the p-contact layer.
18. The uLED of claim 1 , wherein the cathode and the anode comprise a reflective metal.
19. A display device comprising:
a light emitting array comprising: a plurality of singulated micro-light emitting diodes (uLEDs) each comprising:
a mesa comprising:
a plurality of semiconductor layers including an n-type layer, an active layer, and a p-type layer;
a p-contact layer contacting the p-type layer;
the mesa comprising a height spanning from a top surface of the p-contact layer to a bottom surface of the n-type layer and a width spanning a first sidewall of the n-type layer to a second sidewall of the n-type layer; the top surface of the p-contact layer having a different planar orientation compared to the first and second sidewalls of the n-type layer;
a cathode contacting the first sidewall of the n-type layer;
a first region of dielectric material that insulates the p-contact layer, the active layer, and a first sidewall of the p-type layer from the cathode;
an anode contacting the top surface of the p-contact layer; and
a second region of dielectric material that insulates the active layer, a second sidewall of the p-type layer, and the second sidewall of the n-type layer from the anode;
the cathode and the anode longitudinally spanning the uLED; and
a housing including a display face enclosing the plurality of singulated uLEDs.
20. A display system comprising the display device of claim 19 and one or more controllers in communication with the plurality of uLEDs.
21. The display system of claim 20 , wherein the plurality of uLED or groups of the uLEDs are independently controllable.