Optoelectronic device with modulation doping
An improved heterostructure for an optoelectronic device is provided. The heterostructure includes an active region, an electron blocking layer, and a p-type contact layer. The p-type contact layer and electron blocking layer can be doped with a p-type dopant. The dopant concentration for the electron blocking layer can be at most ten percent the dopant concentration of the p-type contact layer. A method of designing such a heterostructure is also described.
1. A heterostructure comprising:
an active region;
a p-type contact layer having a p-type contact layer dopant concentration;
an electron blocking layer located between the active region and the p-type contact layer; and
a p-type interlayer located between the electron blocking layer and the p-type contact layer, wherein the p-type interlayer is immediately adjacent to the electron blocking layer, and wherein the p-type interlayer includes a varying dopant concentration that increases from a dopant concentration comparable to a p-type dopant concentration in the electron blocking layer to a dopant concentration comparable to the p-type contact layer dopant concentration in a direction from the electron blocking layer to the p-type contact layer, and wherein the p-type interlayer further includes a varying semiconductor alloy composition that decreases from a semiconductor alloy composition comparable to a semiconductor alloy composition of the electron blocking layer to a semiconductor alloy composition comparable to a semiconductor alloy composition of the p-type contact layer in a direction from the electron blocking layer to the p-type contact layer.
2. The heterostructure of claim 1 , wherein the p-type dopant concentration in the electron blocking layer is at most ten percent of the p-type contact layer dopant concentration.
3. The heterostructure of claim 1 , wherein an effective lattice constant for the p-type interlayer is between an effective lattice constant for the electron blocking layer and an effective lattice constant for the p-type contact layer.
4. The heterostructure of claim 1 , wherein the varying dopant concentration in the p-type interlayer increases once the varying semiconductor alloy composition in the p-type interlayer is comparable to the semiconductor alloy composition of the p-type contact layer.
5. The heterostructure of claim 1 , further comprising a plurality of thin sublayers located within the electron blocking layer, each thin sublayer having an aluminum molar fraction that is at least 10% higher than an aluminum molar fraction of a remainder of the electron blocking layer.
6. The heterostructure of claim 5 , further comprising a second plurality of thin sublayers located within the p-type interlayer.
7. The heterostructure of claim 5 , wherein each of the plurality of thin sublayers have a n-type dopant concentration of approximately 10 17 to approximately 10 19 dopants per cubic centimeters.
8. The heterostructure of claim 5 , a plurality of gallium nitride (GaN) sublayers located within the electron blocking layer.
9. The heterostructure of claim 8 , wherein each of the plurality of GaN sublayers have a p-type dopant concentration of approximately 5×10 19 dopants per cubic centimeters.
10. The heterostructure of claim 1 , wherein the electron blocking layer, the p-type interlayer, and the p-type contact layer each include a n-type dopant concentration.
11. The heterostructure of claim 10 , wherein a magnitude of the n-type dopant concentration is at most approximately 20% of a magnitude of the p-type dopant concentration.
12. An optoelectronic device comprising:
an n-type contact layer having an n-type doping;
a p-type contact layer having a p-type contact layer dopant concentration;
an active region located between the n-type contact layer and the p-type contact layer;
an electron blocking layer located between the active region and the p-type contact layer; and
a p-type interlayer located between the electron blocking layer and the p-type contact layer, wherein the p-type interlayer is immediately adjacent to the electron blocking layer, and wherein the p-type interlayer includes a varying dopant concentration that increases from a dopant concentration comparable to a p-type dopant concentration in the electron blocking layer to a dopant concentration comparable to the p-type contact layer dopant concentration in a direction from the electron blocking layer to the p-type contact layer, and wherein the p-type interlayer further includes a varying semiconductor alloy composition that continuously decreases from a semiconductor alloy composition comparable to a semiconductor alloy composition of the electron blocking layer to a semiconductor alloy composition comparable to a semiconductor alloy composition of the p-type contact layer in a direction from the electron blocking layer to the p-type contact layer.
13. The device of claim 12 , wherein an effective lattice constant for the p-type interlayer is between an effective lattice constant for the electron blocking layer and an effective lattice constant for the p-type contact layer.
14. The device of claim 12 , wherein the varying dopant concentration in the p-type interlayer increases once the varying semiconductor alloy composition in the p-type interlayer is comparable to the semiconductor alloy composition of the p-type contact layer.
15. The device of claim 12 , further comprising a plurality of thin sublayers located within the electron blocking layer, each thin sublayer having an aluminum molar fraction that is at least 10% higher than an aluminum molar fraction of a remainder of the electron blocking layer.
16. The device of claim 15 , wherein each of the plurality of thin sublayers have a n-type dopant concentration of approximately 10 17 to approximately 10 19 dopants per cubic centimeters.
17. The device of claim 15 , further comprising a plurality of gallium nitride (GaN) sublayers located within the electron blocking layer, and wherein each of the plurality of GaN sublayers have a p-type dopant concentration of approximately 5×10 19 dopants per cubic centimeters.
18. The device of claim 12 , wherein the electron blocking layer, the p-type interlayer, and the p-type contact layer each include a n-type dopant concentration, and wherein a magnitude of the n-type dopant concentration is at most approximately 20% of a magnitude of the p-type dopant concentration.
19. A method of fabricating a device, the method comprising:
creating a device design for the device using a computer system, wherein the device design includes a heterostructure comprising:
an active region;
a p-type contact layer having a target p-type contact layer dopant concentration;
an electron blocking layer located between the active region and the p-type contact layer; and
a p-type interlayer located between the electron blocking layer and the p-type contact layer, wherein the p-type interlayer is immediately adjacent to the electron blocking layer, and wherein the p-type interlayer includes a varying dopant concentration that increases from a dopant concentration comparable to a p-type dopant concentration in the electron blocking layer to a dopant concentration comparable to the p-type contact layer dopant concentration in a direction from the electron blocking layer to the p-type contact layer, and wherein the p-type interlayer further includes a varying semiconductor alloy composition that continuously decreases from a semiconductor alloy composition comparable to a semiconductor alloy composition of the electron blocking layer to a semiconductor alloy composition comparable to a semiconductor alloy composition of the p-type contact layer in a direction from the electron blocking layer to the p-type contact layer; and
providing the device design for use in fabricating the device according to the device design.
20. The method of claim 19 , wherein a growth temperature for the electron blocking layer is higher than a growth temperature for the p-type contact layer.