Light-emitting device and light-emitting apparatus
A light-emitting device includes a semiconductor epitaxial structure that has a first surface and a second surface opposite to the first surface, and that includes a first type semiconductor layer, an active layer, and a second type semiconductor layer sequentially disposed in such order in a thickness direction from the first surface to the second surface. An ohmic contact layer is disposed on the second surface of the semiconductor epitaxial structure, and a light-transmissive dielectric layer is disposed on the ohmic contact layer away from the semiconductor epitaxial structure. The light-transmissive dielectric layer has a plurality of through holes. A reflection layer is disposed on the light-transmissive dielectric layer and fills the through holes so as to be electrically connected to the ohmic contact layer.
1 . A light-emitting device, comprising:
a semiconductor epitaxial structure that has a first surface and a second surface opposite to said first surface, and that includes:
a first type semiconductor layer,
an active layer, and
a second type semiconductor layer sequentially disposed in such order in a thickness direction from said first surface to said second surface, said first surface being a light exiting surface;
an ohmic contact layer that is disposed on said second surface of said semiconductor epitaxial structure,
a light-transmissive dielectric layer that is disposed on said ohmic contact layer away from said semiconductor epitaxial structure and that has a plurality of through holes, each of said through holes having an opening that faces said ohmic contact layer, and
a reflection layer that is disposed on said light-transmissive dielectric layer and that fills said through holes so as to be electrically connected to said ohmic contact layer;
wherein said ohmic contact layer has a first contacting surface that faces said openings of said through holes, and a second contacting surface that contacts said second surface, an area of said first contacting surface of said ohmic contact layer being greater than a total area of said openings of said through holes, an area of said second contacting surface of said ohmic contact layer accounting for 2% to 60% of an area of said second surface.
2 . The light-emitting device as claimed in claim 1 , wherein said area of said second contacting surface of said ohmic contact layer accounts for 4% to 40% of said area of said second surface.
3 . The light-emitting device as claimed in claim 1 , wherein said light-transmissive dielectric layer has a single-layered structure or a multi-layered structure.
4 . The light-emitting device as claimed in claim 1 , wherein said light-transmissive dielectric layer includes one of nitride, oxide, fluoride and combinations thereof.
5 . The light-emitting device as claimed in claim 1 , wherein a refractive index of said second type semiconductor layer is n0, and a refractive index of said light-transmissive dielectric layer is n1, where n0>n1.
6 . The light-emitting device as claimed in claim 1 , wherein said light-transmissive dielectric layer has a thickness greater than 1000 Å.
7 . The light-emitting device as claimed in claim 1 , wherein each of said through holes is defined by a hole-defining surface of said light-transmissive dielectric layer, said hole-defining surface defining each of said through holes is oblique, and forming an included angle with the imaginary plane, said included angle ranging from 20° to 80°.
8 . The light-emitting device as claimed in claim 7 , wherein said included angle ranges from 30° to 70°.
9 . The light-emitting device as claimed in claim 1 , wherein said ohmic contact layer has a patterned structure.
10 . The light-emitting device as claimed in claim 9 , wherein said light-transmissive dielectric layer covers a part of a surface of said ohmic contact layer away from said semiconductor epitaxial structure and a side surface of said ohmic contact layer.
11 . The light-emitting device as claimed in claim 1 , wherein said ohmic contact layer is a transparent conductive layer.
12 . The light-emitting device as claimed in claim 11 , wherein said ohmic contact layer includes one of ZnO, In 2 O 3 , SnO 2 , ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), GZO (Gallium-doped Zinc Oxide) and combinations thereof.
13 . The light-emitting device as claimed in claim 1 , wherein said semiconductor epitaxial structure further includes a current spreading layer disposed on said second type semiconductor layer, and having a recess region and a non-recess region away from said first surface, said ohmic contact layer being disposed on said non-recess region, said light-transmissive dielectric layer being disposed on said non-recess region and said ohmic contact layer away from said semiconductor epitaxial structure.
14 . The light-emitting device as claimed in claim 13 , further comprising a reflection layer disposed on said light-transmissive dielectric layer away from said semiconductor epitaxial structure.
15 . The light-emitting device as claimed in claim 13 , wherein said area of said second contacting surface of said ohmic contact layer is no greater than an area of a surface of said non-recess region contacting said second contacting surface of said ohmic contact layer.
16 . The light-emitting device as claimed in claim 1 , wherein said light-emitting device emits a light having a wavelength that ranges from 550 nm to 950 nm.
17 . A light-emitting apparatus, comprising the light-emitting device as claimed in claim 1 .