Light-emitting diode with hyperbolic metamaterial
A light-emitting diode includes a first semiconductor region of one of p- or n-conductivity types, a second semiconductor region of the other one of p- or n-conductivity types, forming a p-n junction with the first semiconductor region, and a quantum well layer at the p-n junction between the first and second semiconductor regions. A hyperbolic metamaterial structure is provided in the second semiconductor region. The hyperbolic metamaterial structure is coupled to the quantum well layer for extracting light from the quantum well layer. The hyperbolic metamaterial structure may be patterned to provide an array of nanoantennas to apodize the emitted beam, and to control the polarization state of the emitted beam.
1. The A light-emitting diode (LED) comprising:
a first semiconductor region of one of p- or n-conductivity types;
a second semiconductor region of the other one of p- or n-conductivity types, forming a p-n junction with the first semiconductor region;
a quantum well layer at the p-n junction between the first and second semiconductor regions; and
a hyperbolic metamaterial structure in the second semiconductor region, wherein the hyperbolic metamaterial structure is coupled to the quantum well layer;
wherein the hyperbolic metamaterial structure comprises an array of features coupled to the quantum well layer, wherein at least some of the features of the array are inclined with respect to the quantum well layer.
2. The LED of claim 1 , wherein the hyperbolic metamaterial structure comprises a stack of alternating metal and semiconductor layers.
3. The LED of claim 1 , wherein the LED has lateral dimensions of no greater than 25×25 micrometers.
4. The LED of claim 1 , wherein the array of features has a plasmonic resonance optical frequency within a spectral gain band of the quantum well layer.
5. The LED of claim 1 , wherein the array of features has a spatially variant pitch.
6. The LED of claim 1 , wherein the array of features has a spatially varying duty cycle.
7. The LED of claim 1 , wherein a gap between the quantum well layer and features of the array varies across the array.
8. The LED of claim 1 , wherein the array of features is two-dimensional.
9. The LED of claim 1 , wherein each feature of the array comprises at least one of a cylinder feature, a cross feature, or a chevron feature.
10. The LED of claim 1 , wherein the array comprises a plurality of sub-arrays of features, each sub-array comprising an array of grating lines.
11. The LED of claim 1 , wherein the features of the array are configured to provide a pre-defined polarization of emitted light.
12. The LED of claim 1 , wherein features of the array extend from the quantum well layer and into the second semiconductor region.
13. The LED of claim 1 , wherein at least some of the features of the array are inclined towards a center of the array.
14. A display device comprising:
an array of light-emitting diodes, each light-emitting diode comprising:
a first semiconductor region of one of p- or n-conductivity types;
a second semiconductor region of the other one of p- or n-conductivity types, forming a p-n junction with the first semiconductor region;
a quantum well layer at the p-n junction between the first and second semiconductor regions; and
a hyperbolic metamaterial structure in the second semiconductor region, wherein the hyperbolic metamaterial structure is coupled to the quantum well layer;
wherein the hyperbolic metamaterial structure comprises an array of features coupled to the quantum well layer, wherein at least some of the features of the array are inclined with respect to the quantum well layer; and
an element having optical power optically coupled to the array of light-emitting diodes and spaced apart therefrom for redirecting optical beams emitted by the array of light-emitting diodes.
15. The display device of claim 14 , wherein at least some of the features of the array are inclined towards a center of the array.
16. A method of manufacturing a light-emitting diode (LED), the method comprising:
providing a die comprising: a first semiconductor region of one of p- or n-conductivity types; a second semiconductor region of the other one of p- or n-conductivity types forming a p-n junction with the first semiconductor region; and a quantum well layer at the p-n junction between the first and second semiconductor regions; and
forming a hyperbolic metamaterial structure in the second semiconductor region, such that:
the hyperbolic metamaterial structure is coupled to the quantum well layer; and
the hyperbolic metamaterial structure comprises an array of features coupled to the quantum well layer, wherein at least some of the features of the array are inclined with respect to the quantum well layer.
17. The method of claim 16 , wherein forming the hyperbolic metamaterial structure in the second semiconductor region comprises forming a cavity in the second semiconductor region, wherein the hyperbolic metamaterial structure is formed in the cavity.
18. The method of claim 16 , wherein forming the hyperbolic metamaterial structure in the second semiconductor region comprises growing a first portion of the second semiconductor region, forming the hyperbolic metamaterial structure on the portion, and growing a second portion of the second semiconductor region over the hyperbolic metamaterial structure.