Nitride semiconductor ultraviolet light-emitting device
A nitride semiconductor ultraviolet light-emitting device includes at least one first conductivity-type nitride semiconductor layer, a nitride semiconductor emission layer, at least one second conductivity-type nitride semiconductor layer and a transparent conductive film of crystallized Mg x1 Zn 1-x1 O (0<x1<1) that can transmit 75% or more of light emitted from the emission layer, sequentially stacked in this order on a support substrate.
1. A nitride semiconductor ultraviolet light-emitting device comprising:
at least one first conductivity-type nitride semiconductor layer, a nitride semiconductor emission layer, at least one second conductivity-type nitride semiconductor layer and a transparent conductive film of crystallized Mg x1 Z n1-x1 O (0<x1<1) that can transmit 75% or more of light emitted from the emission layer, in this order on a support substrate, wherein the first conductivity-type is a p-type and the second conductivity-type is an n-type.
2. The nitride semiconductor ultraviolet light-emitting device according to claim 1 , wherein the transparent conductive film comprises polycrystalline Mg x1 Z n1-x1 O oriented along its c-axis.
3. The nitride semiconductor ultraviolet light-emitting device according to claim 1 , wherein the transparent conductive film comprises monocrystalline Mg x1 Z n1-x1 O.
4. The nitride semiconductor ultraviolet light-emitting device according to claim 3 , wherein the transparent conductive film of monocrystalline Mg x1 Z n1-x1 O is lattice-matched with the second conductivity-type nitride semiconductor layer.
5. The nitride semiconductor ultraviolet light-emitting device according to claim 1 , wherein the transparent conductive film is non-doped.
6. The nitride semiconductor ultraviolet light-emitting device according to claim 1 , wherein at least one kind of elements of Al, Ga and In is added as impurities into the transparent conductive film.
7. The nitride semiconductor ultraviolet light-emitting device according to claim 1 , wherein the first conductivity-type and the second conductivity-type nitride semiconductor layers are formed with p-type Al x2 Ga 1-x2-y2 In y2 N (0≦x2≦1, 0≦y2≦1, 0≦x2≦1) and n type Al x3 Ga 1-x3-y3 In y3 N (0≦x3≦1, 0≦y3≦1, 0≦x3+y3≦1), respectively.
8. The nitride semiconductor ultraviolet light-emitting device according to claim 1 , wherein light emitted from the emission layer comprises a wavelength in a range of 215 nm to 365 nm.
9. The nitride semiconductor ultraviolet light-emitting device according to claim 1 , wherein the emission layer comprises Al x4 Ga 1-x4-y4 In y4 N (0≦x4≦1, 0≦y4≦1, 0≦x4+y4≦1).
10. The nitride semiconductor ultraviolet light-emitting device according to claim 1 , wherein the support substrate and the first conductivity nitride semiconductor layer are electrically connected to each other with a highly-reflective film intervening therebetween which can reflect 75% or more of light having a wavelength emitted from the emission layer.