Light emitting diode and fabrication method thereof
A light-emitting diode includes: an epitaxial-laminated layer having from bottom up: an n-type ohmic contact layer, a first n-type transition layer, an n-type etching-stop layer, a second n-type transition layer, an n-type confinement layer, an active layer, a p-type confinement layer, a p-type transition layer and a p-type window layer; a p electrode on the upper surface of the p-type window layer; a metal bonding layer over the bottom surface of the n-type ohmic contact layer, wherein, the portion corresponding to the p electrode position extends upwards and passes through the n-type ohmic contact layer and the first n-type transition layer, till the n-type etching-stop layer, thereby forming a current distribution adjustment structure such that the injected current would not flow towards the epitaxial-laminated layer right below the p electrode; and a conductive substrate over the bottom surface of the metal bonding layer.
1. A light-emitting diode, comprising:
an epitaxial-laminated layer, comprising from bottom to up:
an n-type ohmic contact layer;
a first n-type transition layer;
an n-type etching-stop layer;
a second n-type transition layer;
an n-type confinement layer;
an active layer;
a p-type confinement layer;
a p-type transition layer; and
a p-type window layer;
a p electrode over an upper surface of the p-type window layer;
a metal bonding layer over a bottom surface of the n-type ohmic contact layer, wherein: a portion corresponding to a position of the p electrode extends upwards and passes through the n-type ohmic contact layer and the first n-type transition layer, till the n-type etching-stop layer, thereby forming a current distribution adjustment structure such that injected current does not flow towards the epitaxial-laminated layer right below the p electrode; and
a conductive substrate located over a bottom surface of the metal bonding layer.
2. The light-emitting diode of claim 1 , wherein: the n-type etching-stop layer is composed of at least one of InGaP, GaP, GaAs, AlInP, AlAs, or AlGaAs.
3. The light-emitting diode of claim 1 , wherein: the first and second n-type transition layers comprise an AlGaInP layer.
4. The light-emitting diode of claim 1 , wherein: relationship between a width of the p electrode W 1 and a width of the current distribution adjustment structure W 2 is: 1<W 2 /W 1 .
5. The light-emitting diode of claim 1 , wherein: relationship between an area of the p electrode W 1 and an area of the current distribution adjustment structure W 2 is: W 2 /W 1 =1.2.
6. The light-emitting diode of claim 1 , wherein: relationship between a total thickness of the n-type etching-stop layer and the second n-type transition layer T 1 and a thickness of the first n-type transition layer T 2 is: 5<T 2 /T 1 <30.
7. The light-emitting diode of claim 6 , wherein: a thickness of the p-type window layer is 5-10 μm.
8. The light-emitting diode of claim 1 , wherein: the n-type etch-stopping layer has a doping concentration higher than 1E18, and a thickness more than 0.05 μm.
9. The light-emitting diode of claim 1 , wherein: the p-type window layer has a doping concentration higher than 8E17, and a thickness more than 5 μm.
10. The light-emitting diode of claim 1 , wherein: a conductivity of the p-type window layer is higher than that of the first and second n-type transition layers.
11. The light-emitting diode of claim 1 , further comprising a mirror system, located between the n-type ohmic contact layer and the metal bonding layer, which extends towards the current distribution adjustment structure and covers upper surface of the current distribution adjustment structure.
12. The light-emitting diode of claim 11 , wherein: the mirror system also extends and passes through the n-type ohmic contact layer to form a groove.
13. A light-emitting diode fabrication method, comprising:
1) forming an epitaxial-laminated layer, comprising from bottom to up: an n-type ohmic contact layer, a first n-type transition layer, an n-type etching-stop layer, a second n-type transition layer, an n-type confinement layer, an active layer, a p-type confinement layer, a p-type transition layer and a p-type window layer;
2) forming a p electrode on the upper surface of the p-type window layer;
3) forming a metal bonding layer above the bottom surface of the n-type ohmic contact layer, wherein, the portion right below the p electrode position extends upwards and passes through the n-type ohmic contact layer and the first n-type transition layer, till the n-type etching-stop layer, thus forming a current distribution adjustment structure so that the injected current would not flow towards the epitaxial-laminated layer right below the p electrode; and
4) providing a conductive substrate and binding it with the formed metal bonding layer.
14. The method of claim 13 , wherein: step 3) includes:
etching to remove the n-type ohmic contact layer and the first n-type transition layer right below the p electrode via yellow photochemical process, and stopping etching at the n-type etching-stop layer to form a groove;
fabricating a metal bonding layer that fills in the groove structure on the bottom surface of the n-type ohmic contact layer to form a current distribution adjustment structure.
15. The method of claim 14 , wherein: the step 3) further comprises fabrication of a mirror system, including:
etching to remove the n-type ohmic contact layer and the first n-type transition layer right below the p electrode via yellow photochemical process, and stopping etching at the n-type etching-stop layer to form a groove;
fabricating a mirror system on the bottom surface of the n-type ohmic contact layer, which extends towards the groove and covers the side wall and bottom of the groove; and
fabricating a metal bonding layer on the bottom surface of the mirror system, which fills in the groove structure, and forms a current distribution adjustment structure.
16. The method of claim 13 , wherein: material of the n-type etching-stop layer formed in step 1) is InGaP, GaP, GaAs, AlInP, AlAs, or AlGaAs.
17. The method of claim 13 , wherein: the method also comprises: based on luminance efficiency of the light emitting diode, prefer the ratio between the total thickness T 1 of the n-type etching-stop layer and the second n-type transition layer and thickness of the first n-type transition layer T 2 .
18. A light-emitting system comprising a plurality of light-emitting diodes (LEDs), each LED including:
an epitaxial-laminated layer, comprising from bottom to up:
an n-type ohmic contact layer;
a first n-type transition layer;
an n-type etching-stop layer;
a second n-type transition layer;
an n-type confinement layer;
an active layer;
a p-type confinement layer;
a p-type transition layer; and
a p-type window layer;
a p electrode over an upper surface of the p-type window layer;
a metal bonding layer over a bottom surface of the n-type ohmic contact layer, wherein: a portion corresponding to a position of the p electrode extends upwards and passes through the n-type ohmic contact layer and the first n-type transition layer, till the n-type etching-stop layer, thereby forming a current distribution adjustment structure such that injected current does not flow towards the epitaxial-laminated layer right below the p electrode; and
a conductive substrate located over a bottom surface of the metal bonding layer.
19. The system of claim 18 , wherein: relationship between a width of the p electrode W 1 and a width of the current distribution adjustment structure W 2 is: 1<W 2 /W 1 .
20. The system of claim 18 , wherein: relationship between a total thickness of the n-type etching-stop layer and the second n-type transition layer T 1 and a thickness of the first n-type transition layer T 2 is: 5<T 2 /T 1 <30.