Strained AlGaInP layers for efficient electron and hole blocking in light emitting devices
View Patent ↗A light-emitting device is disclosed. The light emitting device includes an electron blocking layer, a hole blocking layer, wherein at least a portion of the hole blocking layer is arranged to have a compressive strain, and an active layer disposed between the hole blocking layer and the electron blocking layer.
1. A light-emitting device, comprising:
an electron blocking layer, wherein at least a portion of the electron blocking layer is arranged to have a tensile strain;
a hole blocking layer, wherein at least a portion of the hole blocking layer is arranged to have a compressive strain; and
an active layer disposed between the hole blocking layer and the electron blocking layer.
2. The light-emitting device of claim 1 , wherein the hole blocking layer has a composition represented as (Al x Ga (1-x) ) 1-y In y P, where 0.4≤x≤1 and 0.49≤y≤0.7.
3. The light-emitting device of claim 1 , wherein the electron blocking layer is formed of a first material from a system of AlGaInP, and the hole blocking layer formed of a second material from a system of AlGaInP that has a greater indium-ratio than the first material.
4. The light-emitting device of claim 1 , wherein:
the hole blocking layer includes a first n-type layer and a second n-type layer,
the first n-type layer is unstrained, and
the second n-type layer is strained compressively.
5. The light-emitting device of claim 4 , wherein the first n-type layer has a composition represented as (Al x Ga (1-x) ) 1-y In y P, where 0.4≤x≤1 and y=0.49.
6. The light-emitting device of claim 1 , wherein the hole blocking layer has a composition represented as (Al x Ga (1-x) ) 1-y In y P, where 0.4≤x≤1 and 0.49≤y≤0.7.
7. A light-emitting device, comprising:
an electron blocking layer;
a hole blocking layer, wherein at least a portion of the hold blocking layer is arranged to have a compressive strain; and
an active layer disposed between the hole blocking layer and the electron blocking layer, the active layer including a first barrier layer arranged to have a tensile strain, a second barrier layer arranged to have a tensile strain, and a well layer disposed between the first barrier layer and the second barrier layer.
8. The light-emitting device of claim 1 , wherein the electron blocking layer has a composition represented as (Al x Ga (1-x) ) 1-y In y P, where 0.4<x<1 and 0.2<y<0.7.
9. The light-emitting device of claim 1 , wherein:
the electron blocking layer includes a first p-type layer and a second p-type layer,
the first p-type layer is unstrained, and
the second p-type layer is arranged to have a tensile strain.
10. The light-emitting device of claim 1 , further comprising a GaAs substrate, wherein:
the hole blocking layer, the electron blocking layer, and the active layer are formed on the same side of the GaAs substrate, and
each of the hole blocking layer, the electron blocking layer, and the active layer is formed of a respective material from a system of AlGaInP.
11. A light-emitting device, comprising:
an electron blocking layer, wherein at least a portion of the electron blocking layer is arranged to have a tensile strain;
a hole blocking layer, wherein at least a portion of the hole blocking layer is arranged to have a compressive strain; and
an active layer formed between the hole blocking layer and the electron blocking layer, the active layer including at least one well structure, the well structure including a first barrier layer that is arranged to have a tensile strain, a second barrier layer that is arranged to have a tensile strain, and a well layer disposed between the first barrier layer and the second barrier layer,
wherein the electron blocking layer is part of one of an upper confinement layer of the light emitting device and a lower confinement layer of the light-emitting device, and
wherein the hole blocking layer is part of the other one of the upper confinement layer of the light emitting device and the lower confinement layer of the light-emitting device.
12. The light-emitting device of claim 11 , wherein the hole blocking layer has a composition represented as (Al x Ga (1-x) ) 1-y In y P, where 0.4<x<1 and 0.49<y<0.7.
13. The light-emitting device of claim 11 , wherein:
the hole blocking layer includes a first n-type layer and a second n-type layer,
the first n-type layer is unstrained,
the second n-type layer is strained compressively,
the first n-type layer has a composition represented as (Al x Ga (1-x) ) 1-y In y P, where 0≤x≤1 and 0.49≤y≤1.
14. The light-emitting device of claim 11 , wherein the electron blocking layer has a composition represented as (Al x Ga (1-x) ) 1-y In y P, where 0.4≤x≤1 and 0.2≤y≤0.7.
15. The light-emitting device of claim 11 , wherein the electron blocking layer includes a first unstrained p-type layer and a second p-type layer that is arranged to have a tensile strain.
16. A light-emitting device, comprising:
an electron blocking layer at least a portion of which is arranged to have a tensile strain;
a hole blocking layer including a first unstrained n-type layer and a second n-type layer that is arranged to have a compressive strain; and
an active layer formed between the hole blocking layer and the electron blocking layer,
wherein the first n-type layer is formed of a first material from a system of AlGaInP, the second n-type layer is formed of a second material from the system of AlGaInP that has a greater indium-ratio than the first material.
17. The light-emitting device of claim 16 , wherein the second n-type layer is situated closer to the active layer than the first n-type layer, and the indium-ratio of the second material is greater than 0.49.
18. The light-emitting device of claim 16 , wherein the second n-type layer has a thickness that is less than a critical thickness associated with the second material.
19. A light-emitting device, comprising:
an electron blocking layer;
a hole blocking layer, the hole blocking layer including a first unstrained n-type layer and a second n-type layer that is arranged to have a compressive strain; and
an active layer formed between the hole blocking layer and the electron blocking layer, the active layer including at least one well structure, the well structure including a first barrier layer that is arranged to have a tensile strain, a second barrier layer that is arranged to have a tensile strain, and a well layer disposed between the first barrier layer and the second barrier layer, and the first barrier layer and the second barrier layer having a composition represented as (Al x Ga (1-x) ) 1-y In y P, where 0.4<x<1 and 0<y<0.49,
wherein the first n-type layer is formed of a first material from a system of AlGaInP, the second n-type layer is formed of a second material from the system of AlGaInP that has a greater indium-ratio than the first material.
20. The light-emitting device of claim 16 , wherein the electron blocking layer includes a first unstrained p-type layer and a second p-type layer that is arranged to have a tensile strain.