Light emitting diode having extensions of electrodes for current spreading
View Patent ↗Disclosed is a light emitting diode having extensions of electrodes for improving current spreading. The light emitting diode includes a lower semiconductor layer, an upper semiconductor layer and an active layer, which are formed on a substrate. The upper semiconductor layer is located above the lower semiconductor layer such that edge regions of the lower semiconductor layer are exposed, and has indents indented in parallel with diagonal directions from positions in the edge regions adjacent to corners of the substrate in a clockwise or counterclockwise direction to expose the lower semiconductor layer. The indents have distal ends spaced apart from each other. Meanwhile, a lower electrode is formed on the exposed region of the lower semiconductor layer corresponding to the first corner of the substrate, and an upper electrode is formed on a transparent electrode layer on the semiconductor layer. Lower extensions extending from the lower electrode are formed on the exposed edge regions of the lower semiconductor layer and on the regions of the lower semiconductor layer exposed through the indents. An upper extension extending from the upper electrode are formed on the transparent electrode layer. The lower and upper extensions improve current spreading, particularly, in a light emitting diode with a large area.
1. A light emitting diode, comprising:
a lower semiconductor layer arranged on a substrate;
an upper semiconductor layer arranged above the lower semiconductor layer such that edge regions of the lower semiconductor layer are exposed, the upper semiconductor layer comprising indents that are parallel with diagonal directions from positions in the edge regions adjacent to corners of the substrate, the indents exposing the lower semiconductor layer and comprising distal ends spaced apart from each other;
an active layer disposed between the lower semiconductor layer and the upper semiconductor layer;
a lower electrode arranged on a first edge region of the edge regions of the lower semiconductor layer, the lower electrode corresponding to a first corner of the corners of the substrate;
a transparent electrode layer arranged on the upper semiconductor layer;
an upper electrode arranged on the transparent electrode layer, the upper electrode corresponding to a second corner of the corners of the substrate;
lower extensions extending from the lower electrode and arranged on a second edge region of the edge regions of the lower semiconductor layer and arranged on regions of the lower semiconductor layer exposed through the indents; and
an upper extension arranged on the transparent electrode layer and extending from the upper electrode.
2. The diode as claimed in claim 1 , wherein the lower extensions arranged on the second edge region of the edge regions of the lower semiconductor layer are terminated at positions spaced apart from the second corner of the corners of the substrate.
3. The diode as claimed in claim 2 , wherein the upper extension comprises:
a first upper extension extending from the upper electrode to the center of the transparent electrode layer; and
a second upper extension, a third upper extension, and a fourth upper extension extending from the center of the transparent electrode layer to other corners of the corners of the substrate excluding the second corner.
4. The diode as claimed in claim 3 , wherein the upper extension further comprises sub-extensions extending from the first upper extension, the second upper extension, the third upper extension, and the fourth upper extensions, the sub-extensions in parallel with the indents, respectively.
5. The diode as claimed in claim 4 , wherein the distal ends of the indents are spaced apart by the same distance from the first upper extension, the second upper extension, the third upper extension, and the fourth upper extension adjacent thereto.
6. The diode as claimed in claim 1 , wherein the transparent electrode layer comprises an opening that exposes a corner of the upper semiconductor layer that corresponds to the second corner of the corners of the substrate, and the upper electrode covers the opening.
7. The diode as claimed in claim 1 , wherein the first corner of the corners of the substrate and the second corner of the corners of the substrate are adjacent to each other.
8. The diode as claimed in claim 7 , further comprising another lower electrode and another upper electrode arranged at other corners of the corners of the substrate opposite to the first corner of the corners of the substrate and the second corner of the corners of the substrate.