Group III nitride based LED structures including multiple quantum wells with barrier-well unit interface layers
Group III nitride based light emitting diode (LED) structures include multiple quantum wells with barrier-well units that include III nitride interface layers. Each interface layer may have a thickness of no greater than about 30% of an adjacent well layer, and a comparatively low concentration of indium or aluminum. One or more interface layers may be present in a barrier-well unit. Multiple barrier-well units having different properties may be provided in a single active region.
1. A light emitting diode comprising:
an active region comprising a plurality of sequentially arranged barrier-well units;
wherein each barrier-well unit comprises a Group III nitride barrier layer comprising a first bandgap and a Group III nitride well layer comprising a second bandgap;
wherein at least one barrier-well unit of the plurality of sequentially arranged barrier-well units, additionally comprises a first Group III nitride interface layer comprising a third bandgap;
wherein the first bandgap is greater than the second bandgap, and the third bandgap is greater than the first bandgap; and
wherein the first Group III nitride interface layer comprises a continuous variation of composition with respect to thickness of the first Group III nitride interface layer.
2. The light emitting diode of claim 1 , wherein fewer than all barrier-well units of the plurality of barrier-well units comprises a first Group III nitride interface layer comprising a third bandgap.
3. The light emitting diode of claim 1 , wherein the first Group III nitride interface layer comprises a thickness of no greater than 10 Å.
4. The light emitting diode of claim 1 , wherein the first Group III nitride interface layer comprises a thickness of no greater than 4 Å.
5. The light emitting diode of claim 1 , wherein the first Group III nitride interface layer comprises a thickness of no greater than about 30% of the Group III nitride well layer.
6. The light emitting diode of claim 1 , wherein in the at least one barrier-well unit, the first Group III nitride interface layer is in contact with the Group III nitride well layer and is in contact with the Group III nitride barrier layer of an adjacent barrier-well unit of the plurality of sequentially arranged barrier-well units.
7. The light emitting diode of claim 1 , wherein at least one barrier-well unit of the plurality of sequentially arranged barrier-well units comprises a second Group III nitride interface layer comprising a fourth bandgap, wherein the fourth bandgap is greater than the second bandgap, and wherein the first bandgap is greater than the fourth bandgap.
8. The light emitting diode of claim 7 , wherein for the at least one barrier-well unit that comprises the second Group III nitride interface layer, the second Group III nitride interface layer is provided between and in contact with the Group III nitride barrier layer and the Group III nitride well layer.
9. The light emitting diode of claim 1 , wherein the first Group III nitride interface layer comprises a linear variation of composition with respect to thickness of the first Group III nitride interface layer.
10. The light emitting diode of claim 1 , wherein the first Group III nitride interface layer comprises a curvilinear variation of composition with respect to thickness of the first Group III nitride interface layer.
11. A light emitting diode comprising:
an active region comprising a plurality of sequentially arranged barrier-well units;
wherein the plurality of sequentially arranged barrier-well units comprises at least one barrier-well unit of a first type, and each barrier-well unit of the first type comprises a Group III nitride barrier layer comprising a first bandgap, a Group III nitride well layer comprising a second bandgap, a first Group III nitride interface layer comprising a third bandgap, and a second Group III nitride interface layer comprising a fourth bandgap;
wherein the third bandgap is greater than the second bandgap, the first bandgap is greater than the third bandgap, and the fourth bandgap is greater than the first bandgap;
wherein the first Group III nitride interface layer comprises a continuous variation of composition with respect to thickness of the first Group III nitride interface layer; and
wherein the second Group III nitride interface layer comprises a continuous variation of composition with respect to thickness of the second Group III nitride interface layer.
12. The light emitting diode of claim 11 , comprising at least one of the following features (a) and (b):
(a) the first Group III nitride interface layer comprises a thickness of no greater than 10 Å;
(b) the second Group III nitride interface layer comprises a thickness of no greater than 10 Å.
13. The light emitting diode of claim 11 , comprising at least one of the following features (a) and (b):
(a) the first Group III nitride interface layer comprises a thickness of no greater than 4 Å;
(b) the second Group III nitride interface layer comprises a thickness of no greater than 4 Å.
14. The light emitting diode of claim 11 , comprising at least one of the following features (a) and (b):
(a) the first Group III nitride interface layer comprises a thickness of no greater than about 30% of a thickness of the Group III nitride well layer;
(b) the second Group III nitride interface layer comprises a thickness of no greater than about 30% of a thickness of the Group III nitride well layer.
15. The light emitting diode of claim 11 , wherein in the at least one barrier-well unit of the first type, the first Group III nitride interface layer is arranged between and in contact with the Group III nitride barrier layer and the Group III nitride well layer, and the second Group III nitride interface layer is arranged in contact with the Group III nitride well layer.
16. The light emitting diode of claim 11 , wherein for the at least one barrier-well-unit of the first type, at least one of the first Group III nitride interface layer or the second Group III nitride interface layer comprises a linear variation of composition with respect to thickness of the first Group III nitride interface layer.
17. The light emitting diode of claim 11 , wherein for the at least one barrier-well-unit of the first type, at least one of the first Group III nitride interface layer or the second Group III nitride interface layer comprises a curvilinear variation of composition with respect to thickness of the first Group III nitride interface layer.
18. The light emitting diode of claim 11 , wherein the plurality of sequentially arranged barrier-well units comprises at least one barrier-well unit of a second type that differs from the first type.