Light emitting diode device
Described are light emitting diode (LED) devices including a combination of electroluminescent quantum wells and photo-luminescent active regions in the same wafer. A first group of QWs with shortest emission wavelength is placed between the p- and n-layers of a p-n junction. Other groups of QWs with longer wavelengths are placed outside the p-n junction in a part of the LED structure where electrical injection of minority carriers does not occur. Electroluminescence emitted by the first group of QWs is absorbed by other group(s) and re-emitted as longer wavelength light. The color of an individual die made on the wafer can be controlled by either etching away unwanted groups of longer-wavelength QWs at the position of that die, or keeping them intact. Wavelength-selective mirrors that increase down conversion efficiency may be selectively applied to die where longer wavelength emission is desired. The use of tunnel junction contacts facilitates integration of wavelength selective mirrors to external surfaces of the die and avoids problems of conductivity type conversion on etched p-GaN layers.
1. A system comprising:
a light emitting diode (LED) device comprising a substrate having a first sub-pixel on a first mesa, a second sub-pixel on a second mesa, and a third sub-pixel on a third mesa thereon, a first trench separating the first sub-pixel and the second sub-pixel, a second trench separating the second sub-pixel and the third sub-pixel, and a dielectric layer formed over at least a portion of the first sub-pixel, the second sub-pixel, and the third sub-pixel, wherein the first mesa has a first mesa tunnel junction on a first mesa electroluminescent quantum well, the second mesa has a second mesa first photoluminescent quantum well and a second mesa second photoluminescent quantum well on a second mesa tunnel junction on a second mesa electroluminescent quantum well, and the third mesa has a third mesa photoluminescent quantum well on a third mesa tunnel junction on a third mesa electroluminescent quantum well;
an LED device attach region having a first electrode coupled to a first anode contact on the first sub-pixel, a second electrode coupled to a second anode contact on the second sub-pixel, and a third electrode coupled to a third anode contact on the third sub-pixel; and
driver circuitry configured to provide independent voltages to one or more of the first electrode, the second electrode, and the third electrode.
2. The system of claim 1 , further comprising a first dichroic mirror on the substrate and a second dichroic mirror on the first dichroic mirror.
3. The system of claim 1 , further comprising a nucleation layer on the substrate and a defect reduction layer on the nucleation layer.
4. The system of claim 1 , wherein the first mesa electroluminescent quantum well, the second mesa electroluminescent quantum well, and the third mesa electroluminescent quantum well independently emit light having a wavelength in a range of from about 410 nm to about 495 nm.
5. The system of claim 1 , wherein the second mesa first photoluminescent quantum well and the third mesa photoluminescent quantum well independently emit light having a wavelength in a range of from about 460 nm to about 570 nm.
6. The system of claim 1 , wherein the second mesa second photoluminescent quantum well emits light having a wavelength in a range of from about 600 nm to about 750 nm.
7. The system of claim 1 , further comprising a first cathode contact in the first trench and a second cathode contact in the second trench.
8. The system of claim 1 , wherein the second mesa first photoluminescent quantum well, the second mesa second photoluminescent quantum well, and the third mesa photoluminescent quantum well independently comprise multiple quantum wells emitting a same wavelength of light.
9. The system of claim 1 , wherein the substrate is a transparent substrate.
10. A system comprising:
a light emitting diode (LED) device comprising a substrate having a first sub-pixel on a first mesa, a second sub-pixel on a second mesa, and a third sub-pixel on a third mesa thereon, a first trench separating the first sub-pixel and the second sub-pixel, a second trench separating the second sub-pixel and the third sub-pixel, and a dielectric layer formed over at least a portion of the first sub-pixel, the second sub-pixel, and the third sub-pixel, wherein the first mesa has a first mesa electroluminescent quantum well on a first mesa tunnel junction, the second mesa has a second mesa first photoluminescent quantum well and a second mesa second photoluminescent quantum well on a second mesa electroluminescent quantum well on a second mesa tunnel junction, and the third mesa has a third mesa photoluminescent quantum well on a third mesa electroluminescent quantum well on a third mesa tunnel junction;
an LED device attach region having a first electrode coupled to a first cathode contact on the first sub-pixel, a second electrode coupled to a second cathode contact on the second sub-pixel, and a third electrode coupled to a third cathode contact on the third sub-pixel; and
driver circuitry configured to provide independent voltages to one or more of the first electrode, the second electrode, and the third electrode.
11. The system of claim 10 , wherein the first mesa electroluminescent quantum well, the second mesa electroluminescent quantum well, and the third mesa electroluminescent quantum well independently emit light having a wavelength in a range of from about 410 nm to about 495 nm.
12. The system of claim 10 , wherein the second mesa first photoluminescent quantum well and the third mesa photoluminescent quantum well independently emit light having a wavelength in a range of from about 460 nm to about 570 nm.
13. The system of claim 10 , wherein the second mesa second photoluminescent quantum well emits light having a wavelength in a range of from about 600 nm to about 750 nm.
14. The system of claim 10 , further comprising a first anode contact in the first trench and a second anode contact in the second trench.
15. The system of claim 10 , wherein the second mesa first photoluminescent quantum well, the second mesa second photoluminescent quantum well, and the third mesa photoluminescent quantum well independently comprise multiple quantum wells emitting a same wavelength of light.
16. The system of claim 10 , wherein the substrate is a transparent substrate.