Ultraviolet light-emitting device with a heavily doped strain-management interlayer

1. A heteroepitaxy strain-management structure for a light emitting device, comprising:

a substrate or template;

an epitaxial layer to be epitaxially formed over the substrate or template, wherein a calculated in-plane compressive strain to be exerted by the substrate or template to the epitaxial layer is equal to or larger than 1%; and

a heavily doped interlayer inserted in-between the epitaxial layer and the substrate or template;

wherein the heavily doped interlayer is of substantially the same material composition as that of the epitaxial layer, with a thickness of 40-400 nm, and doped at a doping level in the range of 5×10 19 to 5×10 20 cm −3 .

2. The heteroepitaxy strain-management structure according to claim 1 , wherein the epitaxial layer is an AlN layer and the substrate is a sapphire substrate, and the heavily doped interlayer is a Si-doped or Ge doped AlN layer with a thickness of 50-175 nm; and

wherein the light emitting device comprises:

the sapphire substrate;

the heavily doped interlayer formed on the sapphire substrate;

the AlN layer directly formed on the heavily doped interlayer;

an n-AlGaN electron supplier layer formed over the AlN layer;

a light emitting active region formed over the n-AlGaN electron supplier layer; and

a p-AlGaN structure formed over the light emitting active region.

3. The heteroepitaxy strain-management structure according to claim 1 , wherein the epitaxial layer is an n-AlGaN electron supplier layer and the template is an AlN layer, and the heavily doped interlayer is a Si-doped or Ge doped AlGaN layer; and

wherein the light emitting device comprises:

the template;

the heavily doped interlayer directly formed on the template;

the n-AlGaN electron supplier layer formed on the heavily doped interlayer;

a light emitting active region formed over the n-AlGaN electron supplier layer; and

a p-AlGaN structure formed over the light emitting active region.

4. An ultraviolet light emitting device comprising:

a substrate;

an AlN layer formed over the substrate;

an n-AlGaN electron supplier layer formed over the AlN layer;

a light emitting active region formed over the n-AlGaN electron supplier layer;

a p-AlGaN structure formed over the light emitting active region;

a p-contact layer formed over the p-AlGaN structure;

wherein a heavily doped AlN interlayer with a doping level equal to or higher than 5×10 19 cm −3 and of a thickness in the range of 40-400 nm is inserted in-between the AlN layer and the substrate, and the AlN layer is directly formed on the heavily doped AlN interlayer.

5. The ultraviolet light emitting device according to claim 4 , wherein the heavily doped AlN interlayer is doped with Si or Ge at a doping level in the range of 5×10 19 to 5×10 20 cm −3 , and of a thickness in the range of 50-175 nm.

6. The ultraviolet light emitting device according to claim 4 , wherein the substrate is a c-plane or a-plane sapphire substrate.

7. The ultraviolet light emitting device according to claim 4 , wherein a calculated in-plane compressive strain to be exerted to the n-AlGaN electron supplier layer by the AlN layer is equal to or larger than 1.0%, and a heavily doped n-AlGaN or n-AlN interlayer with a doping level in the range of 5×10 19 to 5×10 20 cm −3 is inserted in-between the AlN layer and the n-AlGaN electron supplier layer, wherein the n-AlGaN electron supplier layer is directly formed on the heavily doped n-AlGaN or n-AlN interlayer.

8. The ultraviolet light emitting device according to claim 4 , wherein a calculated in-plane compressive strain to be exerted to the p-contact layer by the p-AlGaN structure is equal to or larger than 1.0%, a heavily doped p-AlGaN interlayer with a doping level in the range of 5×10 19 to 5×10 20 cm −3 is inserted in-between the p-AlGaN structure and the p-contact layer, wherein the p-contact layer is directly formed on the heavily doped p-AlGaN interlayer.

9. The ultraviolet light emitting device according to claim 5 , wherein the heavily doped AlN interlayer is of a thickness in the range of 70-150 nm.

10. An ultraviolet light emitting device comprising:

a substrate;

an AlN layer formed over the substrate;

an n-AlGaN electron supplier layer formed over the AlN layer;

a light emitting active region formed over the n-AlGaN electron supplier layer;

a p-AlGaN structure formed over the light emitting active region;

a p-contact layer formed over the p-AlGaN structure;

wherein a first heavily doped n-AlGaN or n-AlN interlayer with a doping level equal to or higher than 5×10 19 cm −3 and of a thickness in the range of 40-400 nm is inserted in-between the AlN layer and the n-AlGaN electron supplier layer, Al-composition of the first heavily doped n-AlGaN interlayer is equal to or larger than Al-composition of the n-AlGaN electron supplier layer, and the n-AlGaN electron supplier layer is directly formed on the first heavily doped n-AlGaN or n-AlN interlayer.

11. The ultraviolet light emitting device according to claim 10 , wherein the first heavily doped n-AlGaN or n-AlN interlayer is doped with Si or Ge at a doping level in the range of 5×10 19 to 5×10 20 cm −3 .

12. The ultraviolet light emitting device according to claim 10 , wherein a heavily doped AlN interlayer with a doping level equal to or higher than 5×10 19 cm −3 and of a thickness in the range of 40-400 nm is inserted in-between the substrate and the AlN layer.

13. The ultraviolet light emitting device according to claim 10 , wherein a second heavily doped n-AlGaN interlayer with a doping level equal to or higher than 5×10 19 cm −3 is inserted in-between the n-AlGaN electron supplier layer and the light emitting active region, Al-composition of the second heavily doped n-AlGaN interlayer is substantially equal to Al-composition of the n-AlGaN electron supplier layer.

14. The ultraviolet light emitting device according to claim 10 , wherein a heavily doped p-AlGaN interlayer with a doping level in the range of 5×10 19 to 5×10 20 cm −3 is inserted in-between the p-AlGaN structure and the p-contact layer.

15. The ultraviolet light emitting device according to claim 11 , wherein the first heavily doped n-AlGaN or n-AlN interlayer is an n-AlGaN layer of a thickness in the range of 100-300 nm.

16. The ultraviolet light emitting device according to claim 11 , wherein the first heavily doped n-AlGaN or n-AlN interlayer is an n-AlN layer of a thickness in the range of 50-175 nm.

17. The ultraviolet light emitting device according to claim 12 , wherein the heavily doped AlN interlayer is doped with Si or Ge at a doping level in the range of 5×10 19 to 5×10 20 cm −3 and of a thickness in the range of 50-175 nm.

18. The ultraviolet light emitting device according to claim 13 , wherein the second heavily doped n-AlGaN interlayer is doped with Si or Ge at a doping level in the range of 5×10 19 to 5×10 20 cm −3 and of a thickness in the range of 40-400 nm.

19. The ultraviolet light emitting device according to claim 14 , wherein the heavily doped p-AlGaN interlayer is doped with Mg at a doping level in the range of 5×10 19 to 5×10 20 cm −3 , of Al-composition equal to or larger than that of the p-contact layer, and of a thickness in the range of 40 to 80 nm.

20. The ultraviolet light emitting device according to claim 18 , wherein the second heavily doped n-AlGaN interlayer is of a thickness in the range of 80-200 nm.