Passivated micro LED structures suitable for energy efficient displays
LED structures passivated with a III-N passivation material including Al. The III-N passivation material may reduce nonradiative recombination, reducing leakage current of an LED structure, and/or improve luminous efficacy. An LED structure may include III-N materials in a multiple quantum well (MQW) structure, and the III-N passivation material including Al may have a wider bandgap than any of the materials in the MQW structure. The III-N passivation material may be AlN, which can be deposited as a binary compound at low temperatures to maintain quality of the MQW structure. The III-N passivation material can be selectively deposited on a sidewall of at least the MQW structure. The III-N passivation material can be unselectively deposited over an LED structure and then etched to form a III-N spacer along a sidewall of at least the MQW structure. Energy efficient RGB micro(μ) LED emissive displays may include passivated LED structures.
1. A light emitting diode (LED) structure, comprising:
a semiconductor material stack comprising a p-type semiconductor material, an n-type semiconductor material, and a multiple quantum well (MQW) structure therebetween, wherein the MQW structure comprises a III-N material layer; and
a passivation material in contact with a sidewall of the MQW structure, but not in contact with any portion of a top surface of the semiconductor material stack, wherein the passivation material comprises a III-N material including Al and
the passivation material is absent from at least a portion of a sidewall of at least one of the p-type and n-type semiconductor materials.
2. The LED structure of claim 1 , wherein the III-N material including Al has a wider band gap than any of the III-N material layers of the MQW structure.
3. The LED structure of claim 2 , wherein the III-N material including Al is predominantly a binary compound of AlN.
4. The LED structure of claim 1 , wherein:
the III-N material layer has an area no more than 100 μm 2 ; and
the III-N material including Al is in direct contact with the III-N material layer.
5. The LED structure of claim 4 , wherein the III-N material including Al has a thickness of 2-100 nm.
6. The LED structure of claim 1 , wherein:
at least one of the p-type and n-type semiconductor materials comprises an impurity-doped III-N material; and
the passivation material is also over a sidewall of one of the p-type and n-type semiconductor materials.
7. The LED structure of claim 1 , wherein:
both the p-type and n-type semiconductor materials comprise impurity-doped III-N materials; and
the passivation material is absent from at least a portion of a sidewall of at least the p-type or n-type semiconductor material that is at a top of the semiconductor material stack.
8. The LED structure of claim 1 , further comprising
at least one of an anode material or a cathode material, and wherein:
the anode or cathode material comprises a conductive oxide having an area substantially equal to that of the top surface of the semiconductor material stack; and
the passivation material is not in contact with any portion of a sidewall of the conductive oxide.
9. The LED structure of claim 1 , wherein the passivation material is absent from at least a portion of a sidewall of the p-type or n-type semiconductor material that is at a bottom of the semiconductor material stack.
10. The LED structure of claim 9 , wherein the passivation material is also over a sidewall one the p-type or n-type semiconductor material that is at a top of the semiconductor material stack.
11. The LED structure of claim 1 , wherein:
the III-N material including Al is predominantly a binary compound of AlN with a wider band gap than any of the III-N material layers of the MQW structure
the III-N material layer has an area no more than 100 μm 2 ; and
the III-N material including Al is in direct contact with the III-N material layer of the MQW.
12. The LED structure of claim 1 , wherein the III-N material comprises GaN layers interleaved with InGaN layers.
13. The LED structure of claim 1 , wherein the passivation material is crystalline, with a c-axis of the passivation material aligned with a c-axis of the MQW structure.
14. An emissive display device, comprising:
a backplane comprising drive circuitry;
a display cover; and
an array of light emitting diode (LED) structures coupled to the backplane, wherein an individual LED structure comprises the LED structure of claim 1 .
15. The display device of claim 14 , further comprising:
a processor coupled to the backplane;
a memory coupled to the processor; and
a battery coupled to at least one of the processor, memory and backplane.
16. The display device of claim 15 , further comprising:
a radio transceiver coupled to the processor, the radio operable over a wireless transmission band.
17. The display device of claim 15 , wherein:
the III-Nmaterial including Al is predominantly is a binary compound of AIN in direct contact with the one or more layers of III-N material;
the one or more layers of III-N material have an area no more than 100 μm 2 ;
the LED structure further comprises an impurity-doped III-N material between the MQW and anode or cathode;
at least one of the anode and cathode comprises a conductive oxide; and
the AIN passivation material is absent from at least a portion of a sidewall surface of at least one of the impurity-doped III-N material or conductive oxide.
18. The emissive display device of claim 14 , wherein the passivation material is absent from at least a portion of a spacing between adjacent ones of the LED structures in the array.
19. The emissive display device of claim 14 , wherein a first of an anode material and a cathode material is between the LED structure and the backplane, and wherein the passivation material is absent from the first of the anode or cathode material.
20. A light emitting diode (LED) structure, comprising:
a p-type impurity-doped III-N semiconductor material, an n-type impurity-doped III-N semiconductor material, and a multiple quantum well (MQW) structure therebetween, wherein the MQW structure comprises a III-N material layer; and
a passivation material over a sidewall of the MQW structure, wherein the passivation material comprises a III-N material including AlN and is absent from a sidewall of at least one of the p-type and n-type impurity-doped III-N semiconductor materials.