Light Emitting Device with Reflective Electrode
A light-emitting device, comprises a semiconductor light emitting stack; and an electrode on the semiconductor light emitting stack, the electrode comprising an adhesion layer, comprising chromium (Cr) or rhodium (Rh); a mirror layer, formed on the adhesion layer and comprising silver (Ag) or aluminum (Al); a barrier layer, formed on the mirror layer and comprising a first pair of metal layers, wherein the first pair of metal layers comprises a first metal layer and a second metal layer different from the first metal layer; and a bonding layer, formed on the barrier layer and comprising gold (Au), wherein from a cross-sectional view, the barrier layer fully covers the mirror layer and the adhesion layer.
1 . A light-emitting device, comprising:
a semiconductor light emitting stack; and
an electrode on the semiconductor light emitting stack, the electrode comprising:
an adhesion layer, comprising chromium (Cr) or rhodium (Rh);
a mirror layer, formed on the adhesion layer and comprising silver (Ag) or aluminum (Al);
a barrier layer, formed on the mirror layer and comprising a first pair of metal layers, wherein the first pair of metal layers comprises a first metal layer and a second metal layer different from the first metal layer; and
a bonding layer, formed on the barrier layer and comprising gold (Au),
wherein from a cross-sectional view, the barrier layer fully covers the mirror layer and the adhesion layer.
2 . The light-emitting device according to claim 1 , wherein a thickness of the first pair of metal layers is greater than or equal to 400 Å.
3 . The light-emitting device according to claim 1 , wherein the first metal layer comprises titanium (Ti), chromium (Cr) or titanium tungsten (TiW), and the second metal layer comprises platinum (Pt) or nickel (Ni).
4 . The light-emitting device according to claim 1 , wherein from a cross-sectional view, the bonding layer fully covers the barrier layer.
5 . The light-emitting device according to claim 1 , wherein a thickness of the adhesion layer is smaller than or equal to 30 Å.
6 . The light-emitting device according to claim 1 , wherein a thickness of the mirror layer is greater than or equal to 1000 Å.
7 . The light-emitting device according to claim 1 , further comprising a transparent conductive layer between the semiconductor light emitting stack and the adhesion layer.
8 . The light-emitting device according to claim 1 , further comprising a plurality of pits between the bonding layer and the semiconductor light emitting stack.
9 . The light-emitting device according to claim 8 , wherein one of the plurality of pits is not filled up by the adhesion layer.
10 . The light-emitting device according to claim 9 , wherein the one of the plurality of pits is not filled up by the mirror layer.
11 . The light-emitting device according to claim 1 , wherein the barrier layer further comprise a second pair of metal layers fully covering the first pair of metal layers.
12 . The light-emitting device according to claim 1 , wherein the adhesion layer is divided into a plurality of adhesion regions.
13 . The light-emitting device according to claim 12 , wherein a thickness of one of the adhesion regions is smaller than or equal to 5 Å.
14 . The light-emitting device according to claim 1 , wherein the barrier layer comprises a first surface contacting the bonding layer and a second surface contacting the mirror layer, and the first surface is more even than the second surface.