III-nitride light emitting devices fabricated by substrate removal
View Patent ↗Devices and techniques for fabricating InAlGaN light-emitting devices are described that result from the removal of light-emitting layers from the sapphire growth substrate. In several embodiments, techniques for fabricating a vertical InAlGaN light-emitting diode structure that result in improved performance and or cost-effectiveness are described. Furthermore, metal bonding, substrate liftoff, and a novel RIE device separation technique are employed to efficiently produce vertical GaN LEDs on a substrate chosen for its thermal conductivity and ease of fabrication.
1. A method comprising:
growing on a growth substrate a III-nitride light emitting structure including a light emitting layer disposed between a p-type layer and an n-type layer, wherein in each of the layers in the III-nitride light emitting structure, the group III element is one or more of In, Al, and Ga;
etching a trench through an entire thickness of III-nitride material grown on the growth substrate;
bonding the III-nitride light emitting structure to a host substrate; and
removing the growth substrate.
2. The method of claim 1 further comprising forming a reflective electrical contact on a side of the III-nitride light emitting structure opposite the growth substrate.
3. The method of claim 2 further comprising:
forming a first bonding layer on the reflective electrical contact; and
forming a second bonding layer on the host substrate;
wherein bonding the III-nitride light emitting structure to a host substrate comprises bonding the first bonding layer to the second bonding layer.
4. The method of claim 1 wherein the trench is a first trench, the method further comprising forming a second trench in the III-nitride light emitting structure, wherein the first and second trenches define an extent of the light emitting layer for an individual light emitting device.
5. The method of claim 1 wherein etching a trench occurs prior to bonding the III-nitride light emitting structure to the host substrate.
6. The method of claim 1 wherein etching a trench occurs after removing the growth substrate.
7. A method comprising:
growing on a growth substrate a III-nitride light emitting structure including a light emitting layer disposed between a p-type layer and an n-type layer, wherein in each of the layers in the III-nitride light emitting structure, the group III element is one or more of In, Al, and Ga;
forming a first electrical contact on a side of the III-nitride light emitting structure opposite the growth substrate;
after forming the first electrical contact, bonding the III-nitride light emitting structure to a host substrate;
removing the growth substrate; and
after removing the growth substrate, etching away a portion of the III-nitride light emitting structure.
8. The method of claim 7 further comprising:
after etching, forming a second electrical contact on a surface of the III-nitride light emitting structure exposed by said etching.
9. The method of claim 7 wherein the III-nitride light emitting structure includes at least one sacrificial layer, wherein etching comprises chemical etching of sacrificial layers.
10. The method of claim 7 wherein etching comprises forming a trench through the III-nitride light emitting structure.
11. The method of claim 7 further comprising patterning the III-nitride light emitting structure after removing the growth substrate and prior to etching.