1. A light emitting device comprising:
a light emitting structure including a first conductivity-type semiconductor layer, a second conductivity-type semiconductor layer, and an active layer including at least one combination of a well layer of a first composition formed of a nitride-semiconductor material having first electronic energy and a barrier layer of a second composition formed of a nitride-semiconductor material having higher electronic energy than the first electronic energy between the first conductivity-type semiconductor layer and the second conductivity-type semiconductor layer; and
an interface layer disposed between the second conductivity-type semiconductor layer and the active layer or between the first conductivity-type semiconductor layer and the active layer, wherein:
the interface layer includes a first layer, a second layer and a third layer having different energy bandgaps, the first layer, the second layer and the third layer of the interface layer are sequentially disposed in a direction from the active layer towards the second conductivity-type semiconductor layer or the first conductivity-type semiconductor layer, the energy bandgaps of the first layer and the second layer are greater than the energy bandgap of the barrier layer in the active layer, the energy bandgaps of the first layer is greater than the energy band gap of the second layer, and the energy bandgap of the third layer is less than the energy bandgap of the barrier layer in the active layer.
2. The light emitting device according to claim 1, wherein the energy bandgap of the first layer is greater than the energy bandgap of the second layer.
3. The light emitting device according to claim 1, wherein an in-plane lattice constant of at least one of the first layer, the second layer and the third layer is greater than an in-plane lattice constant of the barrier layer in the active layer.
4. The light emitting device according to claim 1, wherein an in-plane lattice constant of at least one of the first layer, the second layer and the third layer is equal to an in-plane lattice constant of the barrier layer in the active layer.
5. The light emitting device according to claim 1, wherein an average in-plane lattice constant of the interface layer is greater than an in-plane lattice constant of the barrier layer in the active layer.
6. The light emitting device according to claim 1, wherein an average in-plane lattice constant of the interface layer is equal to an in-plane lattice constant of the barrier layer in the active layer.
7. The light emitting device according to claim 1, wherein the first layer is further disposed after the first layer, the second layer and the third layer are sequentially disposed.
8. The light emitting device according to claim 1, wherein the first layer of the interface layer contacts the active layer.
9. The light emitting device according to claim 1, further comprising a barrier layer provided between the active layer and the interface layer.
10. The light emitting device according to claim 1, wherein each of the first layer, the second layer and the third layer has a formula of AlxInyGa1-x-yN (here, 0\u2266x,y\u22661).
11. The light emitting device according to claim 1, wherein each of the first layer and the second layer has an energy bandgap of 3.4\u02dc4.7 eV.
12. The light emitting device according to claim 1, wherein each of the first layer and the second layer has an in-plane lattice constant of 3.185\u02dc3.2875 \u212b.
13. The light emitting device according to claim 1, wherein the first layer has a thickness of 1\u02dc10 nm.
14. The light emitting device according to claim 1, wherein the sum total of thicknesses of the first layer and the second layer is more than 5 nm.
15. The light emitting device according to claim 1, wherein the sum total of thicknesses of the first layer, the second layer and the third layer is more than 10 nm.
16. The light emitting device according to claim 1, wherein the first conductivity-type semiconductor layer is an N-type semiconductor layer and the second conductivity-type semiconductor layer is a P-type semiconductor layer, or the first conductivity-type semiconductor layer is a P-type semiconductor layer and the second conductivity-type semiconductor layer is an N-type semiconductor layer.
17. The light emitting device according to claim 10, wherein each of the first layer and the second layer has a formula of AlxInyGa1-x-yN (here, 0\u2266y\u22660.82, 0\u2266x\u22660.43).
18. A light emitting device comprising:
a light emitting structure including a first conductivity-type semiconductor layer, a second conductivity-type semiconductor layer, and an active layer including at least one combination of a well layer of a first composition formed of a nitride-semiconductor material having first electronic energy and a barrier layer of a second composition formed of a nitride-semiconductor material having higher electronic energy than the first electronic energy between the first conductivity-type semiconductor layer and the second conductivity-type semiconductor layer; and
an interface layer disposed between the second conductivity-type semiconductor layer and the active layer or between the first conductivity-type semiconductor layer and the active layer, wherein:
the interface layer includes a first layer, a second layer, and the third layer having different energy band gaps, the energy band gaps of the first layer and the second layer are greater than the energy band gap of the barrier layer in the active layer, the energy band gap of the third layer is less than the energy band gap of the barrier layer in the active layer, the first layer, the second layer and the third layer are sequentially disposed in a direction from the active layer towards the second conductivity-type semiconductor layer or the first conductivity-type semiconductor layer, and another first layer is further disposed after the first layer, the second layer and the third layer are sequentially disposed.
19. A light emitting device comprising:
a light emitting structure including a first conductivity-type semiconductor layer, a second conductivity-type semiconductor layer, and an active layer including at least one combination of a well layer of a first composition formed of a nitride-semiconductor material having first electronic energy and a barrier layer of a second composition formed of a nitride-semiconductor material having higher electronic energy than the first electronic energy between the first conductivity-type semiconductor layer and the second conductivity-type semiconductor layer; and
an interface layer disposed between the second conductivity-type semiconductor layer and the active layer or between the first conductivity-type semiconductor layer and the active layer, wherein:
the interface layer includes a first layer, a second layer and a third layer having different energy band gaps, the energy band gaps of the first layer and the second layer are greater than the energy bandgap of the barrier layer in the active layer, the energy band gap of the third layer is less than the energy bandgap of the barrier layer in the active layer, and an in-plane lattice constant of at least one of the first layer, the second layer and the third layer is greater than or equal to an in-plane lattice constant of the barrier layer in the active layer.
20. The light emitting device according to claim 19, wherein an average in-plane lattice constant of the interface layer is greater than or equal to an in-plane lattice constant of the barrier layer in the active layer.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A device for re-engineering of blood vessels, the device comprising:
a substantially tubular structure for surrounding a blood vessel in a body, the tubular structure being composed of a material having multiple components, wherein each component has a resorption rate that is different than other components; and
wherein as each component resorbs in the body, the blood vessel is allowed to expand to the limits allowed by the remaining components and re-engineer itself according to the pressure within the blood vessel.
2. The device of claim 1, wherein each component comprises a different layer of material, wherein each layer of material has a different resorption rate than another layer of material.
3. The device of claim 2, wherein the resorption rate increases sequentially from one layer to the next layer.
4. The device of claim 3, wherein the resorption rate is highest at an inner edge of the tubular structure.
5. The device of claim 3, wherein the resorption rate is lowest at an outer edge of the tubular structure.
6. The device of claim 1, wherein each component comprises a lattice of fibers interwoven with other lattices of fibers, wherein each lattice of fibers has a different resorption rate than another lattice of fibers.
7. The device of claim 1, wherein the blood vessel is a saphenous vein.
8. The device of claim 1, wherein one of the components is poly-lactic-co-glycolic acid.
9. A sheath for arterialization of venous blood vessels in an animal body, the sheath comprising:
a substantially tubular structure for surrounding a venous blood vessel in a body, the tubular structure including a material having multiple components of different resorption rates; and
wherein as each component resorbs in the body, the venous blood vessel expands to the limit allowed by the remaining components and further arterializes.
10. The sheath of claim 9, wherein each component comprises a different layer of material, wherein each layer of material has a different resorption rate than another layer of material.
11. The sheath of claim 9, wherein each component comprises a lattice of fibers interwoven with other lattices of fibers, wherein each lattice of fibers has a different resorption rate than another lattice of fibers.
12. The sheath of claim 9, wherein the venous blood vessel is a saphenous vein.
13. The sheath of claim 9, wherein one of the components is poly-lactic-co-glycolic acid.
14. A method for re-engineering of a blood vessel, the method comprising:
introducing a sheath around an outer surface of a blood vessel; wherein the sheath comprises a substantially tubular structure including multiple components of different resorption rates; and
allowing the blood vessel to re-engineer itself in response to the sheath by expanding to the limit allowed by the remaining components as each component resorbs in the body.
15. The method of claim 14, wherein each component comprises a different layer of material, wherein each layer of material has a different resorption rate than another layer of material.
16. The method of claim 15, wherein the resorption rate increases sequentially from one layer to the next layer.
17. The method of claim 16, wherein the resorption rate is highest at an inner edge of the tubular structure.
18. The method of claim 14, wherein each component comprises a lattice of fibers interwoven with other lattices of fibers, wherein each lattice of fibers has a different resorption rate than another lattice of fibers.
19. The method of claim 14, wherein the blood vessel is a saphenous vein.
20. The method of claim 14, wherein one of the components is poly-lactic-co-glycolic acid.