Light emitting device having protection element and method of manufacturing the light emitting device
View Patent ↗A light emitting device having a monolithic protection element and a method of fabricating the light emitting device are provided. The light emitting device includes: a light emitter having a cathode and an anode; and the resistive protection element connected to the light emitter in parallel through the cathode and the anode. Here, a resistance Rs of the resistive protection element has a value between a forward resistance Rf and a reverse resistance Rr of a current of the light emitter.
1. A light emitting device, comprising:
a lower semiconductor layer;
an active layer formed above a first portion of a first surface of the lower semiconductor layer;
an upper semiconductor layer formed above the active layer;
a first electrode layer formed above the upper semiconductor layer and to be in electrical connection with the upper semiconductor layer;
a second electrode layer formed above a second portion of the first surface of the lower semiconductor and in electrical connection with the lower semiconductor layer, wherein a space extending between the first and the second electrode layers; and
a resistive protection layer formed to fill at least a part of the space between the first and second electrode layers to electrically connect the first and second electrodes,
wherein a resistance Rf is an electrical resistance of the upper semiconductor layer, the active layer, and the lower semiconductor layer when a positive voltage is applied to the first electrode relative to the second electrode,
wherein a resistance Rr is the electrical resistance of the upper semiconductor layer, the active layer, and the lower semiconductor layer when a negative voltage is applied to the first electrode relative to the second electrode, and
wherein a resistance Rs of the resistive protection layer is greater than Rf and less than Rr.
2. The light emitting device of claim 1 , wherein the resistance value Rs is substantially fixed.
3. The light emitting device of claim 1 , further comprising:
a substrate layer formed below the lower semiconductor layer.
4. The light emitting device of claim 1 , wherein the first electrode layer comprises a transparent metal.
5. The light emitting device of claim 1 , wherein the first electrode layer comprises:
a NiZn layer formed above the upper semiconductor layer and to be in electrical connection with the upper semiconductor layer; and
a Ag layer formed above the NiZn layer and in electrical connection with the NiZn layer.
6. The light emitting device of claim 1 , wherein the second electrode layer comprises a stack of Ti, Al, Ti and Au materials.
7. The light emitting device of claim 1 , wherein the resistive protection layer comprises at least one of ZnO, ITO, poly-Si, and a conductive inorganic or organic material.
8. The light emitting device of claim 1 , wherein the resistive protection layer is formed to contact at least a part of a top surface of the first electrode and to contact at least a part of a top surface of the second electrode.
9. The light emitting device of claim 1 ,
wherein the lower semiconductor layer comprises n-GaN material, and
wherein the upper semiconductor layer comprises p-GaN material.
10. The light emitting device of claim 1 , wherein the resistance Rs is substantially at least 100 times as high as Rf.
11. The light emitting device of claim 1 , wherein the resistive protection layer is formed from a thin film with a sheet resistance that range substantially between 100 Ω/sq and 20000 Ω/sq.
12. The light emitting device of claim 1 ,
wherein the resistive protection layer comprises a plurality of resistive protection layer units, and
wherein each resistive protection layer unit is electrically connected with the first and second electrodes such that all resistive protection layer units are electrically parallel with each other.
13. The light emitting device of claim 1 , wherein Rr>>Rs>>Rf.