Light-emitting element and method of manufacturing the same
A light-emitting element includes: a laminated structure body 20 which is formed from a GaN-based compound semiconductor and in which a first compound semiconductor layer 21 including a first surface 21 a and a second surface 21 b that is opposed to the first surface 21 a , an active layer 23 that faces the second surface 21 b of the first compound semiconductor layer 21 , and a second compound semiconductor layer 22 including a first surface 22 a that faces the active layer 23 and a second surface 22 b that is opposed to the first surface 22 a are laminated; a first light reflection layer 41 that is provided on the first surface 21 a side of the first compound semiconductor layer 21 ; and a second light reflection layer 42 that is provided on the second surface 22 b side of the second compound semiconductor layer 22 . The first light reflection layer 41 includes a concave mirror portion 43 , and the second light reflection layer 42 has a flat shape.
1. A light-emitting element, comprising:
a laminated structure body which is formed from a GaN-based compound semiconductor and in which a first compound semiconductor layer including a first surface and a second surface that is opposed to the first surface, an active layer that faces the second surface of the first compound semiconductor layer, and a second compound semiconductor layer including a first surface that faces the active layer and a second surface that is opposed to the first surface are laminated;
a first light reflection layer that is provided on the first surface side of the first compound semiconductor layer; and
a second light reflection layer that is provided on the second surface side of the second compound semiconductor layer, wherein
the first light reflection layer includes a concave mirror portion, and
the second light reflection layer has a flat shape,
a current injection region and a current non-injection region that surrounds the current injection region are provided in the second compound semiconductor layer, and
a shortest distance D CI from an area central point of the current injection region to a boundary between the current injection region and the current non-injection region satisfies the following Expression,
D CI ≥ω 0 /2
provided that,
ω 0 2 ≡(λ 0 /π){ L OR ( R DBR −L OR )} 1/2
where λ 0 represents a wavelength of light that is mainly emitted from the light-emitting element, L OR represents a resonator length, and R DBR represents a radius of curvature of the concave mirror portion of the first light reflection layer.
2. The light-emitting element according to claim 1 , wherein
when a resonator length is set as L OR , a relationship of 1×10 −5 m≤ L OR is satisfied.
3. The light-emitting element according to claim 1 , wherein
when the first light reflection layer is cut out on a virtual plane including a lamination direction of the laminated structure body, a figure that is drawn by an interface, which faces the laminated structure body, of a part of the concave mirror portion of the first light reflection layer is a part of a circle or a part of a parabola.
4. The light-emitting element according to claim 1 , further comprising:
a mode loss operation portion that is provided on the second surface of the second compound semiconductor layer and constitutes a mode loss operation region that operates on an increase and a decrease of an oscillation mode loss;
a second electrode that is formed on the second surface of the second compound semiconductor layer and on the mode loss operation portion; and
a first electrode that is electrically connected to the first compound semiconductor layer, wherein
the second light reflection layer is formed on the second electrode,
a current injection region, a current non-injection/inner region that surrounds the current injection region, and a current non-injection/outer region that surrounds the current non-injection/inner region are formed in the laminated structure body, and
an orthogonal projection image of the mode loss operation region and an orthogonal projection image of the current non-injection/outer region overlap each other.
5. The light-emitting element according to claim 1 , wherein
a radius r′DBR of an effective region in the concave mirror portion of the first light reflection layer satisfies a relationship of ω 0 ≤r′ DBR ≤20·ω 0 .
6. The light-emitting element according to claim 1 , wherein
a relationship of D CI ≥ω 0 is satisfied.
7. The light-emitting element according to claim 1 , wherein
a relationship of R DBR ≤1×10 −3 m is satisfied.
8. The light-emitting element according to claim 1 , further comprising:
a mode loss operation portion that is provided on the second surface of the second compound semiconductor layer and constitutes a mode loss operation region that operates on an increase and a decrease of an oscillation mode loss;
a second electrode that is formed on the second surface of the second compound semiconductor layer and on the mode loss operation portion; and
a first electrode that is electrically connected to the first compound semiconductor layer, wherein
the second light reflection layer is formed on the second electrode,
a current injection region, a current non-injection/inner region that surrounds the current injection region, and a current non-injection/outer region that surrounds the current non-injection/inner region are formed in the laminated structure body, and
an orthogonal projection image of the mode loss operation region and an orthogonal projection image of the current non-injection/outer region overlap each other.
9. The light-emitting element according to claim 1 , wherein
at least two layers of light absorption material layers are formed in the laminated structure body including a second electrode to be parallel to a virtual plane that is occupied by the active layer.
10. The light-emitting element according to claim 1 , wherein
a compound semiconductor substrate is disposed between the first surface of the first compound semiconductor layer and the first light reflection layer.
11. The light-emitting element according to claim 10 , wherein
the compound semiconductor substrate is constituted by a GaN substrate.
12. The light-emitting element according to claim 10 , wherein
the concave mirror portion of the first light reflection layer includes a base portion that is a protruding portion of the compound semiconductor substrate, and a multi-layer light reflection film that is formed on at least a partial surface of the base portion.
13. The light-emitting element according to claim 10 , wherein
the concave mirror portion of the first light reflection layer includes a base portion that is formed on the compound semiconductor substrate, and a multi-layer light reflection film that is formed on at least a partial surface of the base portion.
14. The light-emitting element according to claim 1 , wherein
the first light reflection layer is formed on the first surface of the first compound semiconductor layer.
15. The light-emitting element according to claim 1 , wherein
a value of heat conductivity of the laminated structure body is higher than a value of heat conductivity of the first light reflection layer.
16. The light-emitting element according to claim 1 , wherein
when a radius of curvature of the concave mirror portion of the light-emitting element is set as R DBR , a relationship of R DBR ≤1×10 −3 m is satisfied.
17. The light-emitting element according to claim 1 , wherein
a convex portion is formed at the periphery of the first light reflection layer, and the first light reflection layer does not protrude from the convex portion.
18. A method of manufacturing a light-emitting element, comprising the successive steps of:
forming a laminated structure body which is formed from a GaN-based compound semiconductor and in which a first compound semiconductor layer including a first surface and a second surface that is opposed to the first surface, an active layer that faces the second surface of the first compound semiconductor layer, and a second compound semiconductor layer including a first surface that faces the active layer and a second surface that is opposed to the first surface are laminated on a compound semiconductor substrate;
forming a second electrode and a second light reflection layer on the second compound semiconductor layer;
fixing the second light reflection layer to a support substrate;
thinning the compound semiconductor substrate;
forming a base portion that is a protruding portion in an exposed surface of the compound semiconductor substrate, or forming the base portion that is the protruding portion on the exposed surface of the compound semiconductor substrate; and
forming a first light reflection layer on at least a part of the base portion, and forming a first electrode that is electrically connected to the first compound semiconductor layer, wherein
the base portion constitutes a concave mirror portion, and
the second light reflection layer has a flat shape,
wherein a current injection region and a current non-injection region that surrounds the current injection region are provided in the second compound semiconductor layer, and
a shortest distance D CI from an area central point of the current injection region to a boundary between the current injection region and the current non-injection region satisfies the following Expression,
D CI ≥ω 0 /2
provided that,
ω 0 2 ≡(λ 0 /π){ L OR ( R DBR −L OR )} 1/2
where λ 0 represents a wavelength of light that is mainly emitted from the light-emitting element, L OR represents a resonator length, and R DBR represents a radius of curvature of the concave mirror portion.