Semiconductor light-emitting element
View Patent ↗In a semiconductor light-emitting element, a first cladding layer in a first conductive type, a quantum well active layer, and a second cladding layer in a second conductive type are stacked on a semiconductor substrate in this order. A ridge-shaped stripe formed at the second cladding layer forms a waveguide. Rf<Rr and Wf>Wr are satisfied, where the width of the ridge-shaped stripe at a front end face from which laser light is output is represented by Wf, the width of the ridge-shaped stripe at a rear end face is represented by Wr, the reflectance of the front end face is represented by Rf, and the reflectance of the rear end face is represented by Rr. Light in a fundamental transverse mode, a first high-order transverse mode, a second high-order transverse mode, and a third high-order transverse mode is guided in the waveguide.
1. A semiconductor light-emitting element comprising: a first cladding layer in a first conductive type; a quantum well active layer; and a second cladding layer in a second conductive type, wherein: the first cladding layer, the quantum well active layer and the second cladding layer which are stacked on a semiconductor substrate in this order, a ridge-shaped stripe formed at the second cladding layer forms a waveguide, Rf<Rr and Wf>Wr are satisfied, where a width of the ridge-shaped stripe at a front end face from which laser light is output is represented by Wf, a width of the ridge-shaped stripe at a rear end face opposite to the front end face is represented by Wr, a reflectance of the front end face is represented by Rf, and a reflectance of the rear end face is represented by Rr, a width W of a current injection region at the front end face is less than the width Wf of the ridge-shaped stripe at the front end face, and when (i) an average width Wave of the ridge-shaped stripe is within a range longer than 6 μm and equal to or shorter than 12 μm, (ii) a resonator length is within a range of equal to or longer than 550 μm and equal to or shorter than 1000 μm, and (iii) ΔW is calculated by (Wf−W), ΔW is set at equal to or greater than ((Wave/3−1)−1) μm and equal to or less than ((Wave/3−1)+1) μm.
2. The semiconductor light-emitting element of claim 1 , further comprising:
a contact layer formed on the second cladding layer,
wherein a width Wc of the contact layer at the front end face is less than the width Wf of the ridge-shaped stripe at the front end face.
3. The semiconductor light-emitting element of claim 1 , further comprising:
a current block layer formed on the second cladding layer such that an opening is formed,
wherein a width of the opening of the current block layer at the front end face is less than the width Wf of the ridge-shaped stripe at the front end face.
4. The semiconductor light-emitting element of claim 1 , wherein:
the ridge shaped stripe includes a first region having a first width and a second region having a second width disposed on the first region, and
the first width is greater than the second width.
5. The semiconductor light-emitting element of claim 1 , wherein:
resistance of both side portions of the ridge-shaped stripe in a width direction perpendicular to an extending direction of the ridge-shaped stripe is higher than resistance of a middle portion of the ridge-shaped stripe between the both side portions in the width direction, and
the both side portions include side surfaces of the ridge-shaped stripe, respectively.
6. The semiconductor light-emitting element of claim 1 , wherein
an angle θ satisfies tan(θ)=ΔW 1 /(2L), where a length of a region of the waveguide in which a ridge-shaped stripe width changes in a resonator direction is represented by L and an absolute value of a difference between the ridge-shaped stripe width at a width change start point and the ridge-shaped stripe width at a width change end point is represented by ΔW 1 , and
the angle θ falls within a range of equal to or higher than 0.05° and equal to or lower than 0.15°.
7. The semiconductor light-emitting element of claim 1 , wherein:
the quantum well active layer is a multiple quantum well active layer,
the width Wf of the ridge-shaped stripe at the front end face falls within a range of equal to or greater than 6 μm and equal to or less than 12 μm, and
a total thickness of well layers of the multiple quantum well active layer falls within a range of equal to or greater than 9 nm and equal to or less than 20 nm.
8. The semiconductor light-emitting element of claim 7 , wherein
0≦xw≦0.1 is satisfied, where an atomic composition of each well layer of the multiple quantum well active layer is In xw Ga yw Al 1-xw-yw N, and
a thickness of each well layer of the multiple quantum well active layer falls within a range of equal to or greater than 3 nm and equal to or less than 8 nm.
9. The semiconductor light-emitting element of claim 2 , wherein
the width Wc of the contact layer at the front end face is equal to the width W of the current injection region at the front end face.
10. The semiconductor light-emitting element of claim 1 , wherein
the semiconductor light-emitting element outputs a laser light having a wavelength of 405 nm band.
11. A semiconductor light-emitting element comprising:
a first cladding layer in a first conductive type;
a quantum well active layer; and
a second cladding layer in a second conductive type, wherein:
the first cladding layer, the quantum well active layer and the second cladding layer are stacked on a semiconductor substrate in this order,
a ridge-shaped stripe formed at the second cladding layer forms a waveguide,
Rf<Rr and Wf>Wr are satisfied, where a width of the ridge-shaped stripe at a front end face from which laser light is output is represented by Wf, a width of the ridge-shaped stripe at a rear end face opposite to the front end face is represented by Wr, a reflectance of the front end face is represented by Rf, and a reflectance of the rear end face is represented by Rr,
a width W of a current injection region at the front end face is less than the width Wf of the ridge-shaped stripe at the front end face,
when (i) an average width W ave of the ridge-shaped stripe is within a range of equal to or longer than 10 μm and equal to or shorter than 30 μm, (ii) a resonator length is within a range of equal to or longer than 800 μm and equal to or shorter than 1300 μm, and (iii) ΔW is calculated by (Wf−W), ΔW is set at equal to or greater than 1 μm and equal to or less than ((W ave /4+0.33)+2) μm.
12. The semiconductor light-emitting element of claim 11 , further comprising:
a contact layer formed on the second cladding layer,
wherein a width Wc of the contact layer at the front end face is less than the width Wf of the ridge-shaped stripe at the front end face.
13. The semiconductor light-emitting element of claim 11 , further comprising:
a current block layer formed on the second cladding layer such that an opening is formed,
wherein a width of the opening of the current block layer at the front end face is less than the width Wf of the ridge-shaped stripe at the front end face.
14. The semiconductor light-emitting element of claim 11 , wherein:
the ridge shaped stripe includes a first region having a first width and a second region having a second width disposed on the first region, and
the first width is greater than the second width.
15. The semiconductor light-emitting element of claim 11 , wherein:
resistance of both side portions of the ridge-shaped stripe in a width direction perpendicular to an extending direction of the ridge-shaped stripe is higher than resistance of a middle portion of the ridge-shaped stripe between the both side portions in the width direction, and
the both side portions include side surfaces of the ridge-shaped stripe, respectively.
16. The semiconductor light-emitting element of claim 11 , wherein:
an angle θ satisfies tan(θ)=ΔW 1 /(2L), where a length of a region of the waveguide in which a ridge-shaped stripe width changes in a resonator direction is represented by L and an absolute value of a difference between the ridge-shaped stripe width at a width change start point and the ridge-shaped stripe width at a width change end point is represented by ΔW 1 , and
the angle θ falls within a range of equal to or higher than 0.05° and equal to or lower than 0.15°.
17. The semiconductor light-emitting element of claim 11 , wherein:
the quantum well active layer is a multiple quantum well active layer,
the width Wf of the ridge-shaped stripe at the front end face falls within a range of equal to or greater than 10 μm and equal to or less than 30 μm, and
a total thickness of well layers of the multiple quantum well active layer falls within a range of equal to or greater than 4 nm and equal to or less than 10 nm.
18. The semiconductor light-emitting element of claim 17 , wherein:
0.1≦xw≦0.15 is satisfied, where an atomic composition of each well layer of the multiple quantum well active layer is In xw Ga yw Al 1-xw-yw N, and
a thickness of each well layer of the multiple quantum well active layer falls within a range of equal to or greater than 2 nm and equal to or less than 5 nm.
19. The semiconductor light-emitting element of claim 11 , wherein
ΔW is set at equal to or greater than 2 μm and equal to or less than ((W ave /4+0.33)+1) μm.
20. The semiconductor light-emitting element of claim 12 , wherein
the width Wc of the contact layer at the front end face is equal to the width W of the current injection region at the front end face.
21. The semiconductor light-emitting element of claim 11 , wherein
the semiconductor light-emitting element outputs a laser light having a wavelength of 445 nm band.