Method of fabricating nitride-based semiconductor light-emitting device and nitride-based semiconductor light-emitting device
A nitride-based semiconductor light-emitting device capable of suppressing reduction of characteristics and a yield and method of fabricating the same is described. The method of fabricating includes the steps of forming a groove portion on a nitride-based semiconductor substrate by selectively removing a prescribed region of a second region of the nitride-based semiconductor substrate other than a first region corresponding to a light-emitting portion of a nitride-based semiconductor layer up to a prescribed depth and forming the nitride-based semiconductor layer having a different composition from the nitride-based semiconductor substrate on the first region and the groove portion of the nitride-based semiconductor substrate.
1. A nitride-based semiconductor light-emitting device comprising:
a nitride-based semiconductor substrate;
a first region provided on said nitride-based semiconductor substrate and a second region arranged to be adjacent to said first region through a step portion having a prescribed height; and
a nitride-based semiconductor layer formed on an upper surface of said first region of said nitride-based semiconductor substrate and a side surface of said step portion, wherein
said nitride-based semiconductor layer includes a first conductive type cladding layer, an active layer and a second conductive type cladding layer successively formed from a side closer to said nitride-based semiconductor substrate, said first conductive type cladding layer has a different composition from said nitride-based semiconductor substrate as well as contains Al, Ga and N; and
an Al composition ratio of said first conductive type cladding layer formed on the side surface of said step portion is lower than an Al composition ratio of said first conductive type cladding layer formed on the upper surface of said first region, and
the upper surface of said first region of said nitride-based semiconductor substrate has a (H,K,-H-K,L) plane wherein H and K are integers, and at least either H or K is nonzero, wherein L is any number that allows the Al composition ratio of said first conductive type cladding layer formed on the side surface of said step portion to be lower than the Al composition ratio of said first conductive type cladding layer formed on the upper surface of said first region,
wherein the first conductive type cladding layer comprises a single layer having an Al composition ratio in a portion of the single layer formed on the side surface of the step portion lower than an Al composition ratio in another portion of the corresponding single layer formed on the upper surface of said first region,
wherein a thickness of the portion of the single layer formed on the side surface of the step portion is smaller than a thickness of the another portion of the corresponding single layer formed on the upper surface of the first region.
2. The nitride-based semiconductor light-emitting device according to claim 1 , wherein said step portion has a step-like side surface.
3. The nitride-based semiconductor light-emitting device according to claim 1 , wherein said second conductive type cladding layer has a ridge portion on said first region.
4. The nitride-based semiconductor light-emitting device according to claim 1 , wherein the upper surface of said first region of said nitride-based semiconductor substrate has a (H,K,-H-K,0) plane.
5. The nitride-based semiconductor light-emitting device according to claim 1 , wherein said step portion is so formed as to extend along a [K,-H, H-K,0]direction.
6. The nitride-based semiconductor light-emitting device according to claim 1 , wherein said nitride-based semiconductor layer includes a layer, formed on said first region and said second region of said nitride-based semiconductor substrate, containing Al and Ga and a light-emitting layer of a nitride-based semiconductor formed at least on said first region.
7. The nitride-based semiconductor light-emitting device according to claim 1 , wherein the upper surface of said first region of said nitride-based semiconductor substrate has a (1, −1, 0, L) plane and said step portion is so formed as to extend along a [1, 1, −2,0] direction.
8. The nitride-based semiconductor light-emitting device according to claim 1 , wherein L is an integer.
9. The nitride-based semiconductor light-emitting device according to claim 1 , wherein L is a nonzero integer.
10. The nitride-based semiconductor light-emitting device according to claim 1 , wherein the upper surface of said first region of said nitride-based semiconductor substrate is misoriented by less than ±1.0° from a plane selected from the group consisting of a (1-100) plane, a (11-20) plane, a (11-22) plane, a (11-21) plane, a (11-23) plane, a (11-24) plane, a (11-25) plane, a (2-201) plane, a (1-101) plane, a (1-102) plane, a (1-103) plane, and a (1-104) plane.
11. The nitride-based semiconductor light-emitting device according to claim 7 , wherein the upper surface of said first region of said nitride-based semiconductor substrate is misoriented by less than ±1.0° from a plane selected from the group consisting of a (1-101) plane, a (1-102) plane, a (1-103) plane, and a (1-104) plane.