Semiconductor multilayer film mirror, vertical cavity type light-emitting element using the mirror, and methods for manufacturing the mirror and the element
A semiconductor multilayer film mirror is configured such that a pair of an InAlN-based semiconductor film and a GaN-based semiconductor film is layered a plurality of times in a cyclic fashion and the InAlN-based semiconductor film has an In composition of less than 18 at %. The semiconductor multilayer film mirror includes a thin GaN cap layer formed on the InAlN-based semiconductor film and an AlGaN layer formed on the thin GaN cap layer between each pair of the InAlN-based semiconductor film and the GaN-based semiconductor film.
1. A semiconductor multilayer film mirror comprising:
a plurality of pairs of an InAlN-based semiconductor film and a GaN-based semiconductor film, where each pair of the InAlN-based semiconductor film and the GaN-based semiconductor film is layered in a cyclic fashion, the InAlN-based semiconductor film having an In composition of less than 18 at %; and
a thin GaN cap layer formed on the InAlN-based semiconductor film and an AlGaN layer formed on the thin GaN cap layer, between each pair of the InAlN-based semiconductor film and the GaN-based semiconductor film.
2. The semiconductor multilayer film mirror according to claim 1 , wherein the AlGaN layer has an Al composition satisfying at least a lattice mismatch rate of 0.12% or less with the InAlN-based semiconductor film.
3. The semiconductor multilayer film mirror according to claim 1 , wherein the AlGaN layer has a thickness of at least 3 nm or more.
4. The semiconductor multilayer film mirror according to claim 1 , wherein the AlGaN layer has a graded Al composition.
5. The semiconductor multilayer film mirror according to claim 1 , wherein the AlGaN layer has a layered structure having two or more layers.
6. The semiconductor multilayer film mirror according to claim 1 , wherein the thin GaN cap layer has a thickness of 1 nm or more and 5 nm or less.
7. A vertical cavity type light-emitting element comprising:
a semiconductor multilayer film mirror as a first reflecting mirror comprising: a plurality of pairs of an InAlN-based semiconductor film and a GaN-based semiconductor film, where each pair of the InAlN-based semiconductor film and the GaN-based semiconductor film is layered in a cyclic fashion, the InAlN-based semiconductor film having an In composition of less than 18 at %; and a thin GaN cap layer formed on the InAlN-based semiconductor film and an AlGaN layer formed on the thin GaN cap layer, between each pair of the InAlN-based semiconductor film and the GaN-based semiconductor film;
a first semiconductor layer formed of at least one semiconductor layer on the first reflecting mirror;
an active layer formed on the first semiconductor layer;
a second semiconductor layer formed on the active layer and including at least one semiconductor layer having a conductivity type opposite to that of the first semiconductor layer; and
a second reflecting mirror disposed on the second semiconductor layer so as to be opposed to the first reflecting mirror.
8. The vertical cavity type light-emitting element according to claim 7 , wherein the AlGaN layer has an Al composition satisfying at least a lattice mismatch rate of 0.12% or less with the InAlN-based semiconductor film.
9. The vertical cavity type light-emitting element according to claim 7 , wherein the AlGaN layer has a thickness of at least 3 nm or more.
10. The vertical cavity type light-emitting element according to claim 7 , wherein the AlGaN layer has a graded Al composition.
11. The vertical cavity type light-emitting element according to claim 7 , wherein the AlGaN layer has a layered structure having two or more layers.
12. The vertical cavity type light-emitting element according to claim 7 , wherein the thin GaN cap layer has a thickness of 1 nm or more and 5 nm or less.
13. A method for manufacturing a semiconductor multilayer film mirror by atmospheric pressure metal-organic vapor phase epitaxy, the method comprising:
a layering step of layering a pair of an InAlN-based semiconductor film and a GaN-based semiconductor film a plurality of times in a cyclic fashion, wherein
the layering step includes:
a step of growing the InAlN-based semiconductor film so that the InAlN-based semiconductor film has an In composition of less than 18 at %;
a step of forming a thin GaN cap layer after the step of growing the InAlN-based semiconductor film;
a step of growing an AlGaN layer after the step of growing the thin GaN cap layer; and
a step of growing the GaN-based semiconductor film after the step of growing the AlGaN layer.
14. A method for manufacturing a vertical cavity type light-emitting element by atmospheric pressure metal-organic vapor phase epitaxy, the method comprising:
a step of forming a semiconductor multilayer film mirror under atmospheric pressure, as a first reflecting mirror, comprising: a layering step of layering a pair of an InAlN-based semiconductor film and a GaN-based semiconductor film a plurality of times in a cyclic fashion, wherein the layering step includes:
a step of growing the InAlN-based semiconductor film so that the InAlN-based semiconductor film has an In composition of less than 18 at %;
a step of forming a thin GaN cap layer after the step of growing the InAlN-based semiconductor film;
a step of growing an AlGaN layer after the step of growing the thin GaN cap layer; and
a step of growing the GaN-based semiconductor film after the step of growing the AlGaN layer;
a step of forming a first semiconductor layer formed of at least one semiconductor layer on the first reflecting mirror;
a step of forming an active layer on the first semiconductor layer;
a step of forming a second semiconductor layer, including at least one semiconductor layer having a conductivity type opposite to that of the first semiconductor layer, on the active layer; and
a step of forming a second reflecting mirror on the second semiconductor layer so as to be opposed to the semiconductor multilayer film mirror.