Optical devices

Abstract

The present invention provides an optical device having a well layer made of a group III nitride semiconductor containing high crystal quality In. [Solution] The optical device using a group III nitride semiconductor is made of an n-type group III nitride semiconductor and comprises a pit generation layer 12 that generates a plurality of pits 25, a first periodic structure layer (periodic structure layer 13) formed on the pit generation layer and having a periodic structure in which group III nitride semiconductors of different compositions are alternately stacked, an intermediate layer 16 formed on the first periodic structure layer and made of an n-type group III nitride semiconductor, and a well layer 18 formed on the intermediate layer 16 and made of an undoped group III nitride semiconductor containing In, wherein the pits 25 extend from the pit generation layer 12 to the surface of the well layer 18.

Claims

1. In optical devices using group III nitride semiconductors, It consists of an n-type group III nitride semiconductor, and has a pit-generating layer that generates multiple pits, A first periodic structural layer is formed on the pit-forming layer and has a periodic structure in which group III nitride semiconductors with different In compositions are alternately stacked, An intermediate layer formed on the first periodic structural layer, which is made of an n-type group III nitride semiconductor, The intermediate layer has a well layer made of a non-doped In-containing group III nitride semiconductor, The pit is an optical device that extends from the pit generation layer to the surface of the well layer.

2. The optical device according to claim 1, wherein the emission wavelength of the well layer is 570 nm or more.

3. The optical device according to claim 2, wherein the first periodic structure layer is a quantum well structure in which a first quantum well layer and a first barrier layer are alternately stacked, and the wavelength corresponding to the band gap energy of the first quantum well layer is 380 nm or more and 480 nm or less.

4. Furthermore, the first periodic structural layer has a second periodic structural layer having a periodic structure in which group III nitride semiconductors with different In compositions are alternately stacked. The optical device according to any one of claims 1 to 3, wherein the maximum In composition of the second periodic structural layer is greater than or equal to the maximum In composition of the first periodic structural layer.

5. Furthermore, the first periodic structural layer has a second periodic structural layer having a periodic structure in which group III nitride semiconductors with different In compositions are alternately stacked. The optical device according to any one of claims 1 to 3, wherein the average In composition of the second periodic structural layer is higher than the average In composition of the first periodic structural layer.

6. The optical device according to claim 4, wherein the second periodic structure layer is a quantum well structure in which a second quantum well layer and a second barrier layer are alternately stacked, and the wavelength corresponding to the bandgap energy of the second quantum well layer is 480 nm or more and 580 nm or less.

7. Furthermore, between the pit-generating layer and the first periodic structure layer, there is a third periodic structure layer having a periodic structure in which group III nitride semiconductors with different In compositions are alternately stacked. The optical device according to any one of claims 1 to 3, wherein the maximum In composition of the first periodic structural layer is higher than the maximum In composition of the third periodic structural layer.

8. Furthermore, between the pit-generating layer and the first periodic structure layer, there is a third periodic structure layer having a periodic structure in which group III nitride semiconductors with different In compositions are alternately stacked. The optical device according to any one of claims 1 to 3, wherein the average In composition of the first periodic structural layer is higher than the average In composition of the third periodic structural layer.

9. Furthermore, between the intermediate layer and the well layer, there is a fourth periodic structure layer having a periodic structure in which group III nitride semiconductors with different In compositions are alternately stacked. The optical device according to claim 4, wherein the maximum In composition of the fourth periodic structural layer is greater than or equal to the maximum In composition of the first periodic structural layer and less than or equal to the maximum In composition of the second periodic structural layer.

10. Furthermore, between the intermediate layer and the well layer, there is a fourth periodic structure layer having a periodic structure in which group III nitride semiconductors with different In compositions are alternately stacked. The optical device according to claim 8, wherein the average In composition of the fourth periodic structural layer is lower than the average In composition of the third periodic structural layer.

11. A third barrier layer is formed on the well layer and is made of an undoped group III nitride semiconductor having a larger band gap energy than the well layer, An electron blocking layer formed on the third barrier layer, which is made of an undoped or p-type group III nitride semiconductor having a larger bandgap energy than the well layer, The electron blocking layer has a p-type contact layer made of a p-type group III nitride semiconductor formed on the electron blocking layer, The optical device according to any one of claims 1 to 3, wherein the pits are gradually filled in from the third barrier layer and are filled and disappear in the p-type contact layer.

12. The optical device according to any one of claims 1 to 3, wherein the thickness of the pit-generating layer is 10 nm or more and 250 nm or less.

13. The optical device according to claim 12, wherein the thickness of the pit-generating layer is 150 nm or less.

14. The optical device according to any one of claims 1 to 3, wherein the diameter of the pits on the surface of the pit-generating layer is 10 nm or more and 270 nm or less.

15. The optical device according to any one of claims 1 to 3, wherein the diameter of the pit increases or decreases as it reaches from the pit generation layer to the surface of the well layer.

16. The optical device according to any one of claims 1 to 3, wherein the diameter of the pit on the surface of the well layer is 0.5 to 2 times the diameter of the pit on the surface of the pit generation layer.

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