Contact architectures for tunnel junction devices
A flip chip III-Nitride LED which utilizes a dielectric coating backed by a metallic reflector (e.g., aluminum or silver). High reflectivity and low resistance contacts for optoelectronic devices. Low ESD rating optoelectronic devices. A VCSEL comprising a tunnel junction for current and optical confinement.
1. An optoelectronic device, comprising:
a flip chip III-Nitride light emitting diode (LED);
a dielectric coating on the LED; a metallic reflector backing the dielectric coating; and
a contact metallization to the LED, wherein:
the contact metallization comprises aluminum; and
the contact metallization comprises the metallic reflector and vias through the dielectric coating.
2. The optoelectronic device of claim 1 , further comprising at least one n-type III-Nitride layer for current spreading on at least one side of the LED.
3. The optoelectronic device of claim 1 , further comprising n-type III-Nitride layers for current spreading on both sides of the LED.
4. The optoelectronic device of claim 1 , further comprising a semi-transparent conducting layer as current spreading on the p-side of the LED.
5. The optoelectronic device of claim 4 , wherein the semi-transparent conducting layer is indium tin oxide.
6. The optoelectronic device of claim 4 , wherein the semi-transparent conducting layer is zinc oxide.
7. The device of claim 1 , wherein the metallic reflector consists essentially of aluminum.
8. The device of claim 1 , where the dielectric coating is a multi-layer stack of alternating dielectrics.
9. The optoelectronic device of claim 1 , wherein the metallic reflector has a reflectivity greater than 80% for light having a wavelength of 450 nanometers.
10. The method of claim 9 , wherein:
providing the flip chip LED comprises:
forming a p-n junction structure comprising a p-type III-nitride layer on or above an n-type III-nitride layer; and
forming an n-type III-nitride structure on the p-type III-nitride layer, forming a tunnel junction between the n-type III-nitride structure and the p-type III-nitride layer;
forming the dielectric coating on the n-type III-nitride structure;
forming the vias through the dielectric coating; and wherein the metallic reflector is on the dielectric coating; and the vias contact the n-type III-nitride structure.
11. An optoelectronic device, comprising:
a p-n junction structure comprising a p-type III-nitride layer on or above an n-type III-nitride layer;
an n-type III-nitride structure on the p-type III-nitride layer, forming a tunnel junction between the n-type III-nitride structure and the p-type III-nitride layer;
a dielectric coating on the n-type III-nitride structure;
one or more vias through the dielectric coating; and
metal comprising:
a metallic reflector on the dielectric coating; and
the vias to contact the n-type III-nitride structure, wherein the metal consists essentially of aluminum.
12. The optoelectronic device of claim 11 , wherein, comprising:
the metal comprises an n-type contact (n-contact) to the device, the n-contact having a specific contact resistivity below 1×10 −6 Ωcm 2 .
13. The optoelectronic device of claim 11 , wherein the device is a light emitting diode (LED), edge emitting laser, or vertical cavity surface emitting laser.
14. The optoelectronic device of claim 11 , wherein a reflectivity of the metallic reflector is higher than 80% for light having a wavelength of 450 nm.
15. The optoelectronic device of claim 11 , wherein a subsequent metal stack is deposited on the aluminum for wire bonding or die attachment.
16. A method of making an optoelectronic device, comprising:
providing a flip chip III-Nitride light emitting diode (LED);
providing a dielectric coating on the LED; a metallic reflector backing the dielectric coating; and
depositing a contact metallization to the LED, wherein:
the contact metallization comprises aluminum; and
the contact metallization comprises the metallic reflector and vias through the dielectric coating.
17. The method of claim 16 , wherein the aluminum is a layer deposited and annealed in a low oxygen environment with a partial pressure of oxygen less than 10 −4 torr.
18. The method of claim 16 , wherein the aluminum is a layer annealed at a temperature less than 660° C.
19. The method of 16 , wherein at least 99% of the contact metallization is the aluminum.