Semiconductor light emitting element
Light extraction efficiency of a semiconductor light-emitting element is improved. A buffer layer, an n-type GaN layer, an InGaN emission layer, and a p-type GaN layer are laminated on a sapphire substrate in a semiconductor light-emitting element. A ZnO layer functioning as a transparent electrode is provided on the p-type GaN layer and concave portions are formed on a surface of the ZnO layer at two-dimensional periodic intervals. If a wavelength of light from the InGaN emission layer in the air is λ, an index of refraction of the ZnO layer at the wavelength λ is n zλ , and a total reflection angle at an interface between the ZnO layer and a medium in contact therewith is θ z , a periodic interval L z between adjacent concave portions is set in a range of λ/n zλ ≦L z ≦λ/(n zλ ×(1−sin θ z )).
1. A semiconductor light-emitting element in which an n-type GaN layer, an emission layer, and a p-type GaN layer are laminated on a substrate, wherein:
an Mg x Zn 1−x O layer (0≦x≦0.5) is provided on the p-type GaN layer;
concave or convex portions are formed on a surface of the Mg x Zn 1−x O layer (0≦x≦0.5) at two-dimensional periodic intervals; and
if a wavelength of light from the emission layer in the air is λ, an index of refraction of the Mg x Zn 1−x O layer (0≦x≦0.5) at the wavelength λ is n zλ , and a total reflection angle at an interface between the Mg x Zn 1−x O layer (0≦x≦0.5) and a medium in contact therewith is periodic interval L z between adjacent concave portions or that between adjacent convex portions is in a range of
λ
n
z
λ
≦
L
z
≦
λ
n
z
λ
(
1
-
sin
θ
z
)
.
2. The semiconductor light-emitting element according to claim 1 , wherein concave or convex portions formed on the Mg x Zn 1−x O layer (0≦x≦0.5) are arranged into a tetragonal lattice or triangle lattice form.
3. A semiconductor light-emitting element in which a p-type GaN layer, an emission layer, and an n-type GaN layer are laminated, wherein:
concave or convex portions are formed on a surface of the n-type GaN layer at two-dimensional periodic intervals; and
if a wavelength of light from the emission layer in the air is λ, an index of refraction of the n-type GaN layer at the wavelength λ is n gλ , and a total reflection angle at an interface between the n-type GaN layer and a medium in contact therewith is θ g , a periodic interval L g between adjacent concave portions or that between adjacent convex portions is in a range of
λ
n
g
λ
≦
L
g
≦
λ
n
g
λ
(
1
-
sin
θ
g
)
.
4. The semiconductor light-emitting element according to claim 3 , wherein
concave or convex portions formed on the n-type GaN layer are arranged into a tetragonal lattice or triangle lattice form.
5. A semiconductor light-emitting element in which an n-type GaN layer, an emission layer, and a p-type GaN layer are laminated on a substrate, wherein:
the substrate is an SiC substrate;
concave or convex portions are formed on a surface of the SiC substrate at two-dimensional periodic intervals; and
if a wavelength of light from the emission layer in the air is λ, an index of refraction of the SiC substrate at the wavelength λ is n sλ , a half value width of light from the emission layer in the air is Δλ, the index of refraction of the SiC substrate at the wavelength λ-Δλ is n s(λ−Δλ) , the index of refraction of the SiC substrate at the wavelength λ+Δλ is n s(λ+Δλ) , and a total reflection angle at an interface between the SiC substrate and a medium in contact therewith is θ s , a periodic interval L s , between adjacent concave portions or that between adjacent convex portions is in a range of
min
{
λ
n
s
λ
,
λ
-
Δ
λ
n
s
(
λ
-
Δ
λ
)
,
λ
+
Δ
λ
n
s
(
λ
+
Δλ
)
}
≦
L
s
≦
max
{
λ
n
s
λ
(
1
-
sin
2
θ
s
)
,
λ
-
Δ
λ
n
s
(
λ
-
Δλ
)
(
1
-
sin
2
θ
s
)
,
λ
+
Δ
λ
n
s
(
λ
+
Δλ
)
(
1
-
sin
2
θ
s
)
}
6. The semiconductor light-emitting element according to claim 5 , wherein
concave or convex portions formed on the SiC substrate are arranged into a tetragonal lattice or triangle lattice form.
7. A semiconductor light-emitting element in which an n-type GaN layer, an emission layer, and a p-type GaN layer are laminated on a substrate, wherein:
the substrate is an SiC substrate;
concave or convex portions are formed on a surface of the SiC substrate at two-dimensional periodic intervals;
a Mg x Zn 1−x O layer (0≦x≦0.5) is provided on the p-type GaN layer;
concave or convex portions are formed on the surface of the Mg x Zn 1−x O layer (0≦x≦0.5) at two-dimensional periodic intervals; and
if a wavelength of light from the emission layer in the air is λ, an index of refraction of the Mg x Zn 1−x O layer (0≦x≦0.5) at the wavelength λ is n zλ , and a total reflection angle at an interface between the Mg x Zn 1−x O layer (0≦x≦0.5) and a medium in contact therewith is θ z , a periodic interval L z between adjacent concave portions or that between adjacent convex portions is in a range of
λ
n
z
λ
≦
L
z
≦
λ
n
z
λ
(
1
-
sin
θ
z
)
.
8. The semiconductor light-emitting element according to claim 7 , wherein concave or convex portions formed on the Mg x Zn 1−x O layer (0≦x≦0.5) are arranged into a tetragonal lattice or triangle lattice form.