Semiconductor light-emitting device and manufacturing method therefor
View Patent ↗On a GaAs substrate ( 1 ), are formed a DBR (Distributed Bragg Reflector) ( 3 ), and a light-emitting layer ( 5 ) made of a plurality of layers of Al y Ga z In 1-y-z P (0≦y≦1, 0≦z≦1) above the DBR ( 3 ). A semiconductor layer or a plurality of semiconductor layers ( 6 )-( 10 ) having a number of layers of 1 or more are formed on the light-emitting layer ( 5 ), and a grating pattern for scattering light is formed on a surface of the semiconductor layer ( 9 ) by photolithography and by etching with a sulfuric acid/hydrogen peroxide based etchant. Thus, a semiconductor device small in radiation angle dependence of light emission wavelength, as well as a manufacturing method therefor, are provided.
1. A semiconductor light-emitting device comprising:
a DBR (Distributed Bragg Reflector) and a light-emitting layer supported by at least a substrate comprising GaAs, the DBR being located between the substrate comprising GaAs and the light-emitting layer, wherein light directed from the light-emitting layer toward a top surface of the light-emitting device has a radiation angle dependence;
a semiconductor layer formed over at least the light-emitting layer, a top surface of the semiconductor layer comprising a roughened surface which is not at least partially covered by the other semiconductor layers in order to cause light output from the light-emitting device to be scattered upon leaving the top surface of the device;
wherein no DBR is provided between the light-emitting layer and the semiconductor layer having the top surface that is roughened; and
wherein a top electrode of the device includes a plurality of separate apertures defined therein so as to expose different parts of the roughened surface of the semiconductor layer.
2. The semiconductor light-emitting device according to claim 1 , wherein the light-emitting layer to be formed on the GaAs substrate is a single layer or a plurality of layers made of Al y Ga z In 1-y-z P (0≦y≦1, 0≦z≦1).
3. The light-emitting device of claim 1 , wherein the semiconductor with roughened surface has a lattice constant different by 0.5% or more than that of the substrate comprising GaAs.
4. The light-emitting device of claim 1 , wherein no mirror/reflector is provided between the light-emitting layer and the semiconductor layer having the top surface that is roughened.
5. The semiconductor light-emitting device according to claim 1 , wherein the layer whose top surface is a roughened surface is made of Al y Ga z In 1-y-z P (0≦y≦1, 0≦z≦1).
6. The semiconductor light-emitting device according to claim 5 , wherein the layer whose top surface is a roughened surface has a lattice constant different by 0.5% or more from that of the GaAs substrate.
7. The semiconductor light-emitting device according to claim 1 , wherein the semiconductor layer whose top surface is a roughened surface is made of Al x Ga 1-x As (0≦x≦1).
8. The semiconductor light-emitting device according to claim 7 , wherein the semiconductor layer made of Al x Ga 1-x As (0≦x≦1) is transparent to an emission wavelength.
9. The semiconductor light-emitting device according to claim 7 , wherein the semiconductor layer made of Al x Ga 1-x As (0≦x≦1) has an Al mixed crystal ratio x of 0.5-0.8.
10. The semiconductor light-emitting device according to claim 7 , further comprising an Al y Ga z In 1-y-z P (0≦y≦1, 0≦z≦1)layer for diffusing a current injected from an electrode provided on a light takeout side, the Al y Ga z In 1-y-z P layer being provided between the semiconductor layer made of Al x Ga 1-x As (0≦x≦1) and the light-emitting layer.
11. A semiconductor light-emitting device comprising:
a DBR (Distributed Bragg Reflector) and a light-emitting layer supported by a substrate comprising GaAs, the DBR being located closer to the substrate comprising GaAs than is the light-emitting layer; and
a semiconductor layer formed on the light-emitting layer, and wherein at least part of a top surface of the semiconductor layer is roughened so as to define a roughened surface which is not at least partially covered by the other semiconductor layers in order to cause light output from the light-emitting device to be scattered upon leaving the top surface of the device;
wherein no DBR is provided between the light-emitting layer and the semiconductor layer having, the top surface that is roughened; and
wherein a top electrode of the device includes a plurality of separate apertures defined therein so as to expose different parts of the roughened surface of the semiconductor layer.
12. The semiconductor light-emitting device according to claim 11 , wherein the light-emitting layer is a single layer or a plurality of layers comprising Al y Ga z In 1-y-z P (0≦y≦1, 0≦z≦1).
13. The device of claim 11 , further comprising a current diffusion layer located between at least the light-emitting layer and the semiconductor having the top surface that is roughened, and an etch stop layer provided between the current diffusion layer and said semiconductor layer having the top surface that is roughened.
14. The device of claim 11 , wherein the device includes only one DBR.
15. The light-emitting device of claim 11 , wherein the semiconductor with roughened surface has a lattice constant different by 0.5% or more than that of the substrate comprising GaAs.
16. The light-emitting device of claim 11 , wherein no mirror/reflector is provided between the light-emitting layer and the semiconductor layer having the top surface that is roughened.
17. The semiconductor light-emitting device according to claim 11 , wherein the semiconductor layer whose top surface is a roughened surface comprises Al x Ga 1-x As (0≦x≦1).
18. The semiconductor light-emitting device according to claim 17 , wherein the semiconductor layer comprising Al x Ga 1-x As (0≦x≦1) is transparent to an emission wavelength.