Light emitting diode and manufacturing method therefor
Disclosed are a light emitting diode having an n-doped ohm contact buffer layer and a manufacturing method therefor. In the present invention, a highly n-doped ohm contact buffer layer with an electronic concentration up to 1×10 18 cm 3 is formed on the n side of a light emitting epitaxy layer; when a growth substrate is removed, the n-type ohm contact buffer layer on the surface is exposed, which is a no-nitride polarity-face n-type GaN base material with a lower energy gap; an n-type ohm contact electrode is prepared on the n-type ohm contact buffer layer and follows the Ti/Al ohm contact electrode, which can overcome the problem of the existing vertical gallium nitride-based vertical light emitting diode that the voltage of the thin film GaN base light emitting device is unreliable because the ohm contact electrode on the nitride-face GaN base semiconductor layer is easy to crack due to temperature.
1. A fabrication method for a GaN-based LED epitaxial structure, including:
providing a growth substrate;
forming a GaN-based n-type ohmic contact buffer layer of 3.4 eV or lower bandgap and 1×10 18 cm −3 or higher electron concentration over the growth substrate; and
forming a light-emitting epitaxial layer via epitaxial growth over the n-type ohmic contact buffer layer including an n-type semiconductor layer over the n-type ohmic contact buffer layer, an active layer over the n-type semiconductor layer, and a p-type semiconductor over the active layer;
wherein the LED epitaxial structure comprises:
the n-type ohmic contact buffer layer of 1×10 18 cm −3 or higher electron concentration over the growth substrate, wherein the n-type ohmic contact buffer layer has a non-Nitride-polarity surface for forming an n-type ohmic contact electrode thereon;
the light-emitting epitaxial layer over the n-type ohmic contact buffer layer, including at least the n-type semiconductor layer, the active layer, and the p-type semiconductor layer.
2. The fabrication method according to claim 1 , wherein the n-type ohmic contact buffer layer comprises Al c In d Ga 1-c-d N (0≦c<1, 0≦d<1, c+d<1) formed using epitaxial growth.
3. The fabrication method according to claim 1 , wherein the n-type ohmic contact buffer layer of 1×10 20 cm −3 or higher doping concentration is formed by injecting ion via the ion implantation method.
4. The fabrication method according to claim 1 , wherein the n-type ohmic contact buffer layer is grown at a temperature of 500-600° C. to thereby form the non-Nitride-polarity surface.
5. The fabrication method according to claim 1 , wherein a thickness of the n-type ohmic contact buffer layer is 10 Å-5,000 Å.
6. The fabrication method of claim 1 , further comprising:
providing a heat dissipation base to bond the light-emitting epitaxial layer with the conductive base;
lifting off the growth substrate and exposing the non-Nitride-polarity surface of the n-type ohmic contact buffer layer; and
forming a first electrode over the conductive base and forming a second electrode over the non-Nitride-polarity surface of the n-type ohmic contact buffer layer.
7. The fabrication method according to claim 6 , wherein the n-type ohmic contact buffer layer is Al c In d Ga 1-c-d N (0≦c<1, 0≦d<1, c+d<1) formed using epitaxial growth.
8. The fabrication method according to claim 6 , wherein the n-type ohmic contact buffer layer is grown at a temperature of 500-600° C. to thereby form the non-Nitride-polarity surface.
9. The fabrication method according to claim 6 , wherein the n-type ohmic contact buffer layer has a 1×10 20 cm −3 or higher doping concentration and is formed by injecting ion via the ion implantation method.
10. A GaN-based LED epitaxial structure, including:
a GaN-based n-type ohmic contact buffer layer of 3.4 eV or lower bandgap and 1×10 18 cm −3 or higher electron concentration, wherein the n-type ohmic contact buffer layer has a non-Nitride-polarity surface for forming an n-type ohmic contact electrode thereon; wherein the non-Nitride-polarity surface is formed by removing a growth substrate to expose the surface; and
a light-emitting epitaxial layer over the n-type ohmic contact buffer layer, including at least an n-type semiconductor layer, an active layer, and a p-type semiconductor layer.
11. The GaN-based LED epitaxial structure according to claim 10 , wherein the n-type ohmic contact buffer layer comprises Al c In d Ga 1-c-d N (0≦c<1, 0≦d<1, c+d<1).
12. The GaN-based LED epitaxial structure according to claim 10 , wherein the n-type ohmic contact buffer layer is grown at a temperature of 500-600° C. to thereby form the non-Nitride-polarity surface.
13. The GaN-based LED epitaxial structure according to claim 10 , wherein a thickness of the n-type ohmic contact buffer layer is 10 Å-5,000 Å.
14. The GaN-based LED epitaxial structure according to claim 10 , wherein the n-type ohmic contact buffer layer is Si-doped nitride of 1×10 18 cm −3 or higher doping concentration, or the n-type ohmic contact buffer layer is Si-doped nitride of 1×10 20 cm −3 or higher doping concentration.
15. The GaN-based LED epitaxial structure according to claim 14 , further comprising a Si-doped n-type nitride gradient semiconductor layer between the n-type ohmic contact buffer layer and the light-emitting epitaxial layer.
16. A GaN-based LED chip, including:
a conductive base with a front and a reverse surface;
a light-emitting epitaxial layer over the front surface of the conductive base, including an n-type semiconductor layer, an active layer, and a p-type semiconductor layer;
a GaN-based n-type ohmic contact buffer layer of 3.4 eV or lower bandgap and 1×10 18 cm −3 or higher electron concentration over the n-type semiconductor layer;
a first electrode over the reverse surface of the conductive base; and
a second electrode over the n-type ohmic contact buffer layer;
wherein the n-type ohmic contact buffer layer has a non-Nitride-polarity surface over which the second electrode is formed.
17. The LED chip according to claim 16 , wherein the n-type ohmic contact buffer layer comprises Al c In d Ga 1-c-d N (0≦c<1, 0≦d<1, c+d<1).
18. The LED chip according to claim 16 , wherein the n-type ohmic contact buffer layer is grown at a temperature of 500-600° C. to thereby form the non-Nitride-polarity surface.
19. The LED chip according to claim 16 , wherein a thickness of the n-type ohmic contact buffer layer is 10 Å-5,000 Å.
20. The LED chip according to claim 16 , wherein the n-type ohmic contact buffer layer is Si-doped nitride of 1×10 18 cm −3 or higher doping concentration, or the n-type ohmic contact buffer layer is Si-doped nitride of 1×10 20 cm −3 or higher doping concentration.