Semiconductor light-emitting element and method for manufacturing the same
A semiconductor light-emitting element has a distributed Bragg reflector that is grown by depositing an InAlN layer and a GaN layer a plurality of times in that order on a semipolar plane of a semiconductor substrate, and a semiconductor structure layer that is formed on the distributed Bragg reflector and includes an active layer. The InAlN layer has a plurality of projections on an interface with the GaN layer, and the InAlN layer has a low In region which is formed at the top of each of the plurality of projections and which is lower in In composition than the remaining region.
1. A semiconductor light-emitting element comprising:
a distributed Bragg reflector grown by depositing an InAlN layer and a GaN layer a plurality of times in that order on a semipolar plane of a semiconductor substrate; and
a semiconductor structure layer formed on the distributed Bragg reflector and including an active layer, wherein
the InAlN layer has a plurality of projections on an interface with the GaN layer, and
the InAlN layer has a low In region that is formed at a top of each of the plurality of projections and is lower in In composition than a remaining region.
2. The semiconductor light-emitting element according to claim 1 , wherein
the remaining region has a composition that lattice-matches with the GaN layer, and
the low In region has an In composition lower than the remaining region by 10% or more.
3. The semiconductor light-emitting element according to claim 1 , wherein the low In region of each of the projections has a mean size and a mean height that are insensitive to emitted light from the active layer.
4. The semiconductor light-emitting element according to claim 3 , wherein
the low In region of each of the projections has a mean size of 5 to 10 nm and a mean height of 2 to 4 nm, and
the low In region of each of the projections is disposed at mean intervals of 3 to 8 nm.
5. The semiconductor light-emitting element according to claim 1 , wherein
the semipolar plane is any one selected from a (20-2-1) plane, a (20-21) plane, a (11-22) plane, a (10-1-1) plane, a (30-31) plane, and a (30-3-1) plane.
6. A method for manufacturing a semiconductor light-emitting element, the method comprising:
a step of forming, on a semipolar plane of a semiconductor substrate, a distributed Bragg reflector configured from an InAlN layer and a GaN layer, the InAlN layer having a surface with a plurality of projections, the distributed Bragg reflector being formed by repeating, a plurality of times in the following order, a first step of growing the InAlN layer at a first temperature, a second step of supplying NH 3 to the surface of the InAlN layer at a second temperature lower than the first temperature so as to form a low In region, which is lower in In composition than a remaining region in the InAlN layer, at a top of each of the plurality of projections, and a third step of growing the GaN layer on the surface of the InAlN layer; and
a step of growing a semiconductor structure layer including an active layer on the distributed Bragg reflector.
7. The method for manufacturing a semiconductor light-emitting element according to claim 6 , wherein the second temperature is lower than the first temperature within the range of 10° C. to 20° C.
8. The method for manufacturing a semiconductor light-emitting element according to claim 6 , wherein the third step is performed while the second temperature is being held.
9. The method for manufacturing a semiconductor light-emitting element according to claim 8 , wherein, in the third step, the CaN layer is grown with TEG (triethyl gallium) employed as a supply gas.