Device including a semiconductor layer with graded composition
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 heterostructure can include a p-type interlayer located between the electron blocking layer and the p-type contact layer. In an embodiment, the electron blocking layer can have a region of graded transition. The p-type interlayer can also include a region of graded transition.
1 . An optoelectronic device comprising:
a mounting substrate including a mounting region and contact pads; and
a light source electrically disposed on the mounting region and connected to the contact pads, the light source including a heterostructure, the heterostructure comprising:
a group III nitride active region including a series of alternating quantum wells and barriers, wherein the active region is configured to generate radiation having a peak wavelength within a range of wavelengths;
a group III nitride n-type layer having an n-type doping, the n-type layer located on a first side of the active region;
a group III nitride p-type layer having a p-type dopant concentration, the p-type layer located on a second side of the active region opposite the first side, wherein the p-type layer has a non-uniform p-type doping profile region and at least one area of the p-type layer is transparent to the peak wavelength generated by the active region, wherein the at least one area of the p-type layer that is transparent to the peak wavelength includes an aluminum molar fraction decreasing with respect to distance from the active region and a first region in which the p-type dopant concentration has a first inclination with respect to distance from the active region and a second region in which the p-type dopant concentration has a second inclination with respect to distance from the active region, wherein the second inclination is different from the first inclination;
a group III nitride electron blocking layer located between the active region and the p-type layer; and
a set of contact layers connected to the contact pads, where the set of pads includes a p-type contact layer, wherein a doping concentration for p-type doping in the group Ill nitride electron blocking layer is substantially less than that of a doping concentration of the p-type doping in the p-type contact layer.
2 . The optoelectronic device of claim 1 , further comprising:
a p-type electrode electrically connected to the p-type layer, wherein the p-type electrode comprises at least one conductive layer; and
an n-type electrode electrically connected to the n-type layer, wherein the n-type electrode comprises at least one conductive layer.
3 . The optoelectronic device of claim 1 , further comprising a substrate located adjacent to the n-type layer.
4 . The optoelectronic device of claim 1 , wherein the electron blocking layer includes a plurality of sublayers formed by alternating a sublayer of higher aluminum content with a sublayer of lower aluminum content.
5 . The optoelectronic device of claim 1 , further comprising a group III nitride p-type transition region located between the electron blocking layer and the p-type layer, the p-type transition region including 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 dopant concentration in the p-type layer in a direction from the electron blocking layer to the p-type layer.
6 . The optoelectronic device of claim 1 , further comprising a dislocation located in the p-type layer.
7 . The optoelectronic device of claim 1 , wherein at least one region of the p-type layer has a lowest composition of aluminum of the group III nitride layers of the heterostructure.
8 . The optoelectronic device of claim 1 , wherein the at least the one area of the p-type layer that is transparent to the peak wavelength generated by the active region includes aluminum.
9 . The optoelectronic device of claim 1 , wherein the n-type layer includes a short period superlattice that is transparent to the peak wavelength generated by the active region, wherein the short period superlattice includes aluminum.
10 . An optoelectronic device comprising:
a mounting substrate including a mounting region and contact pads; and
a light source electrically disposed on the mounting region and connected to the contact pads, the light source including a heterostructure, the heterostructure comprising:
a group III nitride active region including a series of alternating quantum wells and barriers, wherein the active region is configured to generate radiation having a peak wavelength within a range of wavelengths;
a group III nitride n-type layer having an n-type doping, the n-type layer located on a first side of the active region;
a group III nitride p-type layer having a p-type dopant concentration, the p-type layer located on a second side of the active region opposite the first side, wherein the p-type layer has a non-uniform p-type doping profile and at least one area of the p-type layer has a different transparency to the peak wavelength generated by the active region than another area of the p-type layer, wherein the at least one area of the p-type layer having the different transparency includes an aluminum molar fraction decreasing with respect to distance from the active region and a first region in which the p-type dopant concentration has a first inclination with respect to distance from the active region and a second region in which the p-type dopant concentration has a second inclination with respect to distance from the active region, wherein the second inclination is different from the first inclination;
a group III nitride electron blocking layer located between the active region and the p-type layer; and
a set of contact layers connected to the contact pads, where the set of contact layers includes a p-type contact layer, wherein a doping concentration for p-type doping in the group Ill nitride electron blocking layer is substantially less than that of a doping concentration of the p-type doping in the p-type contact layer.
11 . The optoelectronic device of claim 10 , further comprising:
a p-type electrode electrically connected to the p-type layer, wherein the p-type electrode comprises at least one conductive layer; and
an n-type electrode electrically connected to the n-type layer, wherein the n-type electrode comprises at least one conductive layer.
12 . The optoelectronic device of claim 10 , wherein the electron blocking layer includes a plurality of sublayers formed by alternating a sublayer of higher aluminum content with a sublayer of lower aluminum content.
13 . The optoelectronic device of claim 10 , further comprising a group III nitride p-type transition region located between the electron blocking layer and the p-type layer, the p-type transition region including 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 dopant concentration in the p-type layer in a direction from the electron blocking layer to the p-type layer.
14 . The optoelectronic device of claim 10 , wherein at least one region of the p-type layer has a lowest composition of aluminum of the group III nitride layers of the heterostructure.
15 . The optoelectronic device of claim 10 , wherein the at least the one area of the p-type layer that has a different transparency to the peak wavelength generated by the active region includes aluminum.
16 . The optoelectronic device of claim 10 , wherein the n-type layer includes a short period superlattice that is transparent to the peak wavelength generated by the active region, wherein the short period superlattice includes aluminum.
17 . An optoelectronic device comprising:
a mounting substrate including a mounting region and contact pads; and
a light source electrically disposed on the mounting region and connected to the contact pads, the light source including a heterostructure, the heterostructure comprising:
a group III nitride active region including a series of alternating quantum wells and barriers, wherein the active region is configured to generate radiation having a peak wavelength within a range of wavelengths;
a group Ill nitride n-type layer having an n-type doping, the n-type layer located on a first side of the active region;
a group III nitride p-type layer having a p-type dopant concentration, the p-type layer located on a second side of the active region opposite the first side, wherein at least one area of the p-type layer is transparent to the peak wavelength generated by the active region, wherein the at least one area of the p-type layer that is transparent to the peak wavelength includes an aluminum molar fraction decreasing with respect to distance from the active region and a first region in which the p-type dopant concentration remains substantially constant and a second region in which the p-type dopant concentration is increasing with respect to distance from the active region;
a group Ill nitride electron blocking layer located between the active region and the p-type layer;
a p-type electrode electrically connected to the group Ill nitride p-type layer, wherein the p-type electrode comprises at least one conductive layer wherein a doping concentration for p-type doping in the group Ill nitride electron blocking layer is substantially less than that of a doping concentration of the p-type doping in the p-type electrode; and
an n-type electrode electrically connected to the group Ill nitride n-type layer, wherein the n-type electrode comprises at least conductive layer.
18 . The optoelectronic device of claim 17 , wherein the electron blocking layer includes a plurality of sublayers formed by alternating a sublayer of higher aluminum content with a sublayer of lower aluminum content.
19 . The optoelectronic device of claim 17 , further comprising a group III nitride p-type transition region located between the electron blocking layer and the p-type layer, the p-type transition region including 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 dopant concentration in the p-type layer in a direction from the electron blocking layer to the p-type layer.
20 . The optoelectronic device of claim 17 , wherein the n-type layer includes a short period superlattice that is transparent to the peak wavelength generated by the active region.