Nitride semiconductor laser element and illumination light source module
Provided is a nitride semiconductor laser element which includes: a stacked structure including a plurality of semiconductor layers including a light emitting layer, the stacked structure including a pair of resonator end faces located on opposite ends; and a protective film including a dielectric body and disposed on at least one of the pair of resonator end faces. The protective film includes a first protective film (a first emission surface protective film), a second protective film (a second emission surface protective film), and a third protective film (a third emission surface protective film) disposed in stated order above the stacked structure. The first protective film is amorphous, the second protective film is crystalline, and the third protective film is amorphous.
1. A nitride semiconductor laser element, comprising:
a stacked structure including a plurality of semiconductor layers including a light emitting layer, the stacked structure including a pair of resonator end faces located on opposite ends; and
a protective film including a dielectric body and disposed on at least one of the pair of resonator end faces, wherein:
the protective film includes a first protective film, a second protective film, and a third protective film disposed in stated order above the stacked structure,
the first protective film is amorphous,
the second protective film is crystalline,
the third protective film is amorphous,
the protective film further includes a reflectance adjusting layer disposed above the third protective film and including at least one dielectric film, and
the at least one dielectric film included in the reflectance adjusting layer includes an amorphous oxide film having a noble gas atom concentration less than 3 atomic percent.
2. The nitride semiconductor laser element according to claim 1 , wherein
the second protective film is an aluminum nitride film or an aluminum oxynitride film each of which includes a hexagonal polycrystalline film having a c-axis orientation normal to the at least one of the pair of resonator end faces.
3. The nitride semiconductor laser element according to claim 2 , wherein
the aluminum nitride film or the aluminum oxynitride film includes a crystal having an orientation different from the c-axis orientation.
4. The nitride semiconductor laser element according to claim 2 , wherein
the aluminum nitride film or the aluminum oxynitride film includes an amorphous portion.
5. The nitride semiconductor laser element according to claim 1 , wherein
a total film thickness of the first protective film and the second protective film is less than 50 nm.
6. The nitride semiconductor laser element according to claim 1 , wherein
a film thickness of the first protective film is less than 1.0 nm.
7. The nitride semiconductor laser element according to claim 1 , wherein
the first protective film is an amorphous film containing silicon nitride or silicon oxynitride.
8. The nitride semiconductor laser element according to claim 1 , wherein
the third protective film is an amorphous film containing aluminum oxide or aluminum oxynitride.
9. The nitride semiconductor laser element according to claim 1 , wherein
the first protective film and the second protective film each have a noble gas atom concentration less than 1 atomic percent, and
the third protective film has a noble gas atom concentration greater than or equal to 1 atomic percent and less than 3 atomic percent.
10. The nitride semiconductor laser element according to claim 1 , wherein
the second protective film has a noble gas atom concentration less than a noble gas atom concentration of the first protective film.
11. The nitride semiconductor laser element according to claim 1 , wherein
the first protective film has a noble gas atom concentration less than a noble gas atom concentration of the third protective film.
12. The nitride semiconductor laser element according to claim 1 , wherein
the second protective film has a noble gas atom concentration less than a noble gas atom concentration of the third protective film.
13. The nitride semiconductor laser element according to claim 1 , wherein
the protective film further includes a fourth protective film disposed between the third protective film and the reflectance adjusting layer, the fourth protective film containing nitride or oxynitride.
14. The nitride semiconductor laser element according to claim 13 , wherein
the fourth protective film is a hexagonal polycrystalline film containing aluminum nitride or aluminum oxynitride, and
a crystal orientation of the fourth protective film is a c-axis orientation normal to the at least one of the pair of resonator end faces.
15. The nitride semiconductor laser element according to claim 13 , wherein
the fourth protective film has a noble gas atom concentration less than 1 atomic percent and a film thickness less than 50 nm.
16. The nitride semiconductor laser element according to claim 1 , wherein
the at least one of the pair of resonator end faces has a reflectance that is a maximum value or a minimum value of a reflectance spectrum with respect to a wavelength of laser emitted by the nitride semiconductor laser element.
17. An illumination light source module, comprising:
the nitride semiconductor laser element according to claim 1 .
18. The nitride semiconductor laser element according to claim 1 , wherein
the second protective film and the first protective film contain different elements from each other.
19. The nitride semiconductor laser element according to claim 1 , wherein
the first protective film is an amorphous film containing silicon nitride or silicon oxynitride, and
the second protective film is an aluminum nitride film or an aluminum oxynitride film.
20. A nitride semiconductor laser element, comprising:
a stacked structure including a plurality of semiconductor layers including a light emitting layer, the stacked structure including a pair of resonator end faces located on opposite ends; and
a protective film including a dielectric body and disposed on at least one of the pair of resonator end faces, wherein:
the protective film includes a first protective film, a second protective film, a third protective film disposed in stated order above the stacked structure, a reflectance adjusting layer disposed above the third protective film and including at least one dielectric film, and a fourth protective film disposed between the third protective film and the reflectance adjusting layer,
the first protective film is amorphous,
the second protective film is crystalline,
the third protective film is amorphous,
the fourth protective film contains nitride or oxynitride, and
the at least one dielectric film included in the reflectance adjusting layer includes a dielectric film that is in contact with the fourth protective film, and is an amorphous oxide film having a noble gas atom concentration less than 2 atomic percent.