Waveguide device having delta doped active region
Embodiments of the invention include a laser structure having a delta doped active region for improved carrier confinement. The laser structure includes an n-type cladding layer, an n-type waveguide layer formed adjacent the n-type cladding layer, an active region formed adjacent the n-type waveguide layer, a p-type waveguide layer formed adjacent the active region, and a p-type cladding layer formed adjacent the p-type waveguide layer. The laser structure is configured so that a p-type dopant concentration increases across the active region from the n-type side of the active region to the p-type side of the active region and/or an n-type dopant concentration decreases across the active region from the n-type side of the active region to the p-type side of the active region. The delta doped active region provides improved carrier confinement, while eliminating the need for blocking layers, thereby reducing stress on the active region caused thereby.
1. A semiconductor laser device, comprising:
an n-type cladding layer;
an n-type waveguide layer formed adjacent to the n-type cladding layer;
an active region formed adjacent to the n-type waveguide layer;
a p-type waveguide layer formed adjacent to the active region; and
a p-type cladding layer formed adjacent to the p-type waveguide layer, wherein the device is delta doped in such a way that at least one of a p-type dopant concentration across at least the entire active region increases from a first concentration to a second concentration wherein the second concentration is greater than the first concentration, and an n-type dopant concentration across at least the entire active region decreases from a third concentration to a fourth concentration wherein the third concentration is greater than the fourth concentration.
2. The device as recited in claim 1 , wherein the first position is an interface between the active region and the n-type waveguide layer and the second position is an interface between the active region and the p-type waveguide layer, and wherein the third position is the interface between the active region and the n-type waveguide layer and the fourth position is the interface between the active region and the p-type waveguide layer.
3. The device as recited in claim 1 , wherein the device is doped in such a way that at least one of a p-type dopant concentration increases from a minimum concentration in at least a portion of one of the n-type cladding layer and the n-type waveguide layer, across the active region to a maximum concentration in at least a portion of one of the p-type waveguide layer and the p-type cladding layer, and an n-type dopant concentration decreases from a maximum concentration in at least a portion of one of the n-type cladding layer and the n-type waveguide layer, across the active region to a minimum concentration in at least a portion of one of the p-type waveguide layer and the p-type cladding layer.
4. The device as recited in claim 1 , wherein the first position is within the n-type waveguide layer and the second position is within the p-type waveguide layer, and wherein the third position is within the n-type waveguide layer and the fourth position is within the p-type waveguide layer.
5. The device as recited in claim 1 , wherein the first position is within the n-type cladding layer and the second position is within the p-type cladding layer, and wherein the third position is within the n-type cladding layer and the fourth position is within the p-type cladding layer.
6. The device as recited in claim 1 , wherein the active region includes at least one of an undoped portion at the interface between the active region and the n-type waveguide layer and an undoped portion at the interface between the active region and the p-type waveguide layer, wherein the undoped portion does not include p-type dopant or n-type dopant.
7. The device as recited in claim 1 , wherein the p-type dopant concentration has a maximum concentration within the range from approximately 3.0×10 18 to approximately 1.5×10 19 atoms per cubic centimeter (atoms/cc) at the first position.
8. The device as recited in claim 1 , wherein the n-type dopant concentration has a maximum concentration with the range of approximately 3.0×10 18 to approximately 1.5×10 19 atoms per cubic centimeter (atoms/cc) at the third position.
9. The device as recited in claim 1 , wherein the p-type dopant includes magnesium (Mg).
10. The device as recited in claim 1 , wherein the n-type dopant includes silicon (Si).
11. The device as recited in claim 1 , wherein the active region is indium gallium nitride (InGaN), the p-type waveguide layer and the n-type waveguide layer are gallium nitride (GaN), and the p-type cladding layer and the n-type cladding layer are aluminum gallium nitride (AlGaN).
12. An optical storage device, comprising:
a semiconductor laser light source configured to direct laser light toward an optical storage medium, wherein the semiconductor laser light source includes
an n-type cladding layer,
an n-type waveguide layer formed adjacent to the n-type cladding layer,
an active region formed adjacent to the n-type waveguide layer,
a p-type waveguide layer formed adjacent to the active region, and
a p-type cladding layer formed adjacent to the p-type waveguide layer,
wherein the semiconductor laser light source is delta doped in such a way that at least one of a p-type dopant concentration across at least the entire active region increases from a first concentration to a second concentration wherein the second concentration is greater than the first concentration, and an n-type dopant concentration across at least the entire active region decreases from a third concentration to a fourth concentration wherein the third concentration is greater than the fourth concentration; and
a light receiver configured to receive light reflected off of the optical storage medium,
wherein the light reflected off of the optical storage medium is indicative of information stored on the optical storage medium.
13. The device as recited in claim 12 , wherein the semiconductor laser light source is doped in such a way that at least one of a p-type dopant concentration increases from a minimum concentration in at least a portion of one of the n-type cladding layer and the n-type waveguide layer, across the active region to a maximum concentration in at least a portion of one of the p-type waveguide layer and the p-type cladding layer, and an n-type dopant concentration decreases from a maximum concentration in at least a portion of one of the n-type cladding layer and the n-type waveguide layer, across the active region to a minimum concentration in at least a portion of one of the p-type waveguide layer and the p-type cladding layer.