Electroluminescent device and fabrication method thereof
An electroluminescent device includes a conduction substrate, a reflection layer, a patterned transparent conduction layer, at least one light emitting diode (LED) element, a first contact electrode and a second contact electrode. The reflection layer is disposed on the conduction substrate, and the patterned transparent conduction layer is formed on the reflection layer. The LED element is formed on the patterned transparent conduction layer, and the LED element includes a first semiconductor layer, a light emitting layer and a second semiconductor layer in sequence. The second semiconductor layer is disposed on the patterned transparent conduction layer and the reflection layer. The first contact electrode is disposed at one side of the first semiconductor layer, and the second contact electrode is disposed at one side of the conduction substrate.
1. A fabrication method of an electroluminescent device, comprising steps of:
providing a plate;
forming at least one light emitting diode (LED) element on the plate, wherein the LED element comprises a first semiconductor layer, a light emitting layer and a second semiconductor layer in sequence formed on the plate;
forming a patterned transparent conduction layer on the LED element;
forming a reflection layer on the patterned transparent conduction layer;
attaching a conduction substrate to the reflection layer;
removing the plate; and
forming a first contact electrode and a second contact electrode at one side of the first semiconductor layer and one side of the conduction substrate, respectively.
2. The fabrication method of claim 1 , wherein a rough structure or an anti-reflection layer is formed on the side of the first semiconductor layer and at a position without the first contact electrode.
3. The fabrication method of claim 1 , wherein the conduction substrate is attached to the reflection layer by an adhering layer, the reflection layer is an ohmic contact metal layer, and the reflection layer comprises Pt, Au, Ag, Pd, Ni, Cr, Ti, Al or their combinations.
4. The fabrication method of claim 3 , wherein the adhering layer comprises silver paste, tin paste, tin-silver paste, a eutectic bonding material, metal or a conductive adhering material, which is a material containing lead or containing no lead.
5. The fabrication method of claim 1 , wherein the conduction substrate and the reflection layer have properties of high thermal conductivity, and the conduction substrate comprises a semiconductor material or a metal.
6. The fabrication method of claim 5 , wherein the semiconductor material comprises Si, GaAs, GaP, SiC, BN or their combinations and the metal comprises Al, Cu, Ag, Au, Ni or their combinations.
7. The fabrication method of claim I, wherein the reflection layer is uneven in surface.
8. The fabrication method of claim 7 , wherein the patterned transparent conduction layer comprises a plurality of island-like structures, the island-like structures are independent or continuous, and the island-like structure has a cross section with a rectangular, circular, polygonal or an irregular shape.
9. The fabrication method of claim 1 , wherein the patterning method is dry etching or wet etching, accompanied by physical etching and/or chemical etching.