Light-emitting device
A light-emitting device includes a group III nitride semiconductor layer of a multilayer structure consisting of a group III nitride semiconductor having a major surface defined by a nonpolar plane or a semipolar plane and having at least an n-type layer and a p-type layer. A surface of the group III nitride semiconductor layer on a light extraction side is a mirror surface. The light-emitting device may further include a transparent electrode in contact with the surface of the group III nitride semiconductor layer on the light extraction side. In this case, a surface of the transparent electrode on the light extraction side is preferably a mirror surface.
1. A light-emitting device comprising a group III nitride semiconductor layer of a multilayer structure consisting of a group III nitride semiconductor having a major surface defined by a nonpolar plane or a semipolar plane and having at least an n-type layer and a p-type layer, the light-emitting device further comprising:
an electrode is provided on the surface of the group III nitride semiconductor layer, wherein the electrode is a p-side electrode; and
a light output in a c-axis direction is not less than five times a light output in an a-axis direction as to light outputs of a light emitting layer from the nonpolar plane or the semipolar plane,
wherein the light-emitting device is a laser diode having a pair of end faces parallel to a c-plane,
wherein the major surface of the group III nitride semiconductor layer is defined by an m-plane, and
wherein a major growth surface of the light emitting layer is defined by the m-plane, and polarization of light is stronger in the a-axis direction than in other directions.
2. The light-emitting device according to claim 1 , wherein
the electrode is in the form of stripes.
3. The light-emitting device according to claim 1 , wherein
the electrode is in the form of stripes along the c-axis direction.
4. The light-emitting device according to claim 1 , wherein
the end faces are defined by cleavage planes.
5. The light-emitting device according to claim 1 , having an insulating film between the electrode and the group III nitride semiconductor layer.
6. The light-emitting diode according to claim 1 , wherein
the p-side electrode has not less than two contact regions to the group III nitride semiconductor layer.
7. The light-emitting diode according to claim 1 , wherein one of the pair of end faces, which is a +c-axis-side end face, is covered with a single first film, and the other of the pair of end faces, which is a −c-axis-side end face, is covered with a multiple film formed by alternately repetitively stacking the first film and a second film.
8. The light-emitting diode according to claim 7 ,
wherein the single first film has a thickness of λ/2n 1 , wherein λ represents emission wavelength of the light emitting layer, and n 1 represents a refractive index of the first film,
wherein, in the multiple film, each of the first film has a thickness of λ/4n 1 , and each of the second film has a thickness of λ/4n 2 , where n 2 represents a refractive index of the second film.
9. The light-emitting diode according to claim 7 , wherein the first film is made of ZrO 2 , and the second film is made of SiO 2 .